[fix](load) Fix the sensitivity issue of load column mapping with expressions

[0AyanamiRei]

What problem does this PR solve?

Issue Number: close #xxx

Related PR: #58353 #56041

Problem Summary:

CREATE TABLE t (
    c1 INT,
    c2 VARCHAR(256),
    DATA_DT DATETIME
)
DUPLICATE KEY(c1)
DISTRIBUTED BY HASH(c1) BUCKETS 3
PROPERTIES("replication_num" = "1");

LOAD LABEL load
(
   SET (data_dt = now())
)

The column names in the SET (data_dt = now()) statement here should be case-insensitive.

Release note

None

Check List (For Author)

• Test

  • Regression test
  • Unit Test
  • Manual test (add detailed scripts or steps below)
  • No need to test or manual test. Explain why:
    • This is a refactor/code format and no logic has been changed.
    • Previous test can cover this change.
    • No code files have been changed.
    • Other reason

• Behavior changed:

  • No.
  • Yes.

• Does this need documentation?

  • No.
  • Yes.

Check List (For Reviewer who merge this PR)

• Confirm the release note
• Confirm test cases
• Confirm document
• Add branch pick label

[hello-stephen]

Thank you for your contribution to Apache Doris.
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Please clearly describe your PR:

1. What problem was fixed (it's best to include specific error reporting information). How it was fixed.
2. Which behaviors were modified. What was the previous behavior, what is it now, why was it modified, and what possible impacts might there be.
3. What features were added. Why was this function added?
4. Which code was refactored and why was this part of the code refactored?
5. Which functions were optimized and what is the difference before and after the optimization?

[0AyanamiRei]

run buildall

[liaoxin01]

LGTM

[github-actions]

PR approved by at least one committer and no changes requested.

[github-actions]

PR approved by anyone and no changes requested.

[hello-stephen]

FE UT Coverage Report

Increment line coverage 0.00% (0/1) 🎉
Increment coverage report
Complete coverage report

[doris-robot]

TPC-H: Total hot run time: 35413 ms

machine: 'aliyun_ecs.c7a.8xlarge_32C64G'
scripts: https://github.com/apache/doris/tree/master/tools/tpch-tools
Tpch sf100 test result on commit c71068f9e2e2e64d1fe7d67a0e2b8bf364d50af7, data reload: false

------ Round 1 ----------------------------------
q1	17645	4284	4131	4131
q2	2021	358	242	242
q3	10169	1371	788	788
q4	10199	822	319	319
q5	7447	2151	1955	1955
q6	197	171	136	136
q7	1030	879	719	719
q8	9359	1494	1238	1238
q9	7098	5410	5439	5410
q10	6909	2389	1971	1971
q11	525	320	309	309
q12	739	737	594	594
q13	17774	3700	3019	3019
q14	302	308	278	278
q15	602	509	510	509
q16	700	674	623	623
q17	685	784	549	549
q18	7883	6978	6948	6948
q19	1138	961	636	636
q20	410	374	245	245
q21	4266	4012	3848	3848
q22	1016	1039	946	946
Total cold run time: 108114 ms
Total hot run time: 35413 ms

----- Round 2, with runtime_filter_mode=off -----
q1	4225	4149	4174	4149
q2	335	401	308	308
q3	2159	2641	2320	2320
q4	1354	1775	1323	1323
q5	4236	4764	4689	4689
q6	230	170	130	130
q7	2012	2083	1853	1853
q8	2742	2659	2514	2514
q9	7510	7510	7546	7510
q10	3135	3294	2853	2853
q11	594	515	498	498
q12	941	737	598	598
q13	3592	4060	3255	3255
q14	325	317	315	315
q15	571	534	519	519
q16	676	782	714	714
q17	1277	1510	1352	1352
q18	7832	7673	7601	7601
q19	918	912	930	912
q20	1998	2106	1970	1970
q21	4781	4225	4280	4225
q22	1100	1011	974	974
Total cold run time: 52543 ms
Total hot run time: 50582 ms

[doris-robot]

TPC-DS: Total hot run time: 176105 ms

machine: 'aliyun_ecs.c7a.8xlarge_32C64G'
scripts: https://github.com/apache/doris/tree/master/tools/tpcds-tools
TPC-DS sf100 test result on commit c71068f9e2e2e64d1fe7d67a0e2b8bf364d50af7, data reload: false

query5	4414	597	428	428
query6	338	244	234	234
query7	4255	479	279	279
query8	332	257	244	244
query9	8788	2555	2574	2555
query10	510	393	325	325
query11	15522	15274	14503	14503
query12	190	129	126	126
query13	1288	515	403	403
query14	6413	3033	2777	2777
query14_1	2681	2669	2710	2669
query15	223	210	190	190
query16	944	462	435	435
query17	1144	743	603	603
query18	2612	449	356	356
query19	246	282	202	202
query20	121	112	110	110
query21	220	134	124	124
query22	3872	3849	3882	3849
query23	16714	16073	15925	15925
query23_1	15952	16138	15974	15974
query24	7390	1638	1249	1249
query24_1	1220	1233	1230	1230
query25	551	464	407	407
query26	1247	311	160	160
query27	2705	459	313	313
query28	4444	2146	2149	2146
query29	788	528	451	451
query30	311	242	216	216
query31	852	700	631	631
query32	83	65	69	65
query33	538	319	285	285
query34	902	895	549	549
query35	772	812	722	722
query36	876	916	829	829
query37	129	90	76	76
query38	2843	2878	2829	2829
query39	762	731	701	701
query39_1	700	767	707	707
query40	224	137	120	120
query41	68	61	64	61
query42	104	108	105	105
query43	439	447	416	416
query44	1376	764	742	742
query45	193	194	182	182
query46	871	980	617	617
query47	1671	1693	1630	1630
query48	322	324	246	246
query49	619	433	357	357
query50	659	297	227	227
query51	3820	3796	3768	3768
query52	110	107	100	100
query53	313	348	294	294
query54	292	246	246	246
query55	80	79	74	74
query56	295	300	285	285
query57	1136	1131	1084	1084
query58	265	252	244	244
query59	2355	2517	2429	2429
query60	315	311	286	286
query61	161	155	155	155
query62	729	679	620	620
query63	330	305	318	305
query64	5026	1434	1117	1117
query65	4030	3946	3954	3946
query66	1432	453	330	330
query67	16227	15776	14733	14733
query68	7888	963	753	753
query69	509	354	316	316
query70	1074	1000	992	992
query71	375	317	283	283
query72	6221	2665	5396	2665
query73	766	732	319	319
query74	8903	8844	8763	8763
query75	3213	3163	2805	2805
query76	3933	1128	737	737
query77	526	392	300	300
query78	9462	9562	8943	8943
query79	1595	944	618	618
query80	1246	666	548	548
query81	573	265	241	241
query82	428	127	102	102
query83	260	254	238	238
query84	253	116	100	100
query85	945	513	473	473
query86	409	307	299	299
query87	3046	3019	3024	3019
query88	3345	2300	2318	2300
query89	475	431	393	393
query90	1997	163	160	160
query91	173	165	142	142
query92	71	74	61	61
query93	1281	913	570	570
query94	535	299	286	286
query95	571	379	310	310
query96	604	470	214	214
query97	2278	2321	2223	2223
query98	221	197	191	191
query99	1253	1291	1219	1219
Total cold run time: 261547 ms
Total hot run time: 176105 ms

[doris-robot]

ClickBench: Total hot run time: 27.35 s

machine: 'aliyun_ecs.c7a.8xlarge_32C64G'
scripts: https://github.com/apache/doris/tree/master/tools/clickbench-tools
ClickBench test result on commit c71068f9e2e2e64d1fe7d67a0e2b8bf364d50af7, data reload: false

query1	0.05	0.05	0.05
query2	0.09	0.05	0.05
query3	0.25	0.08	0.08
query4	1.61	0.11	0.12
query5	0.29	0.26	0.24
query6	1.16	0.63	0.63
query7	0.03	0.03	0.03
query8	0.06	0.04	0.04
query9	0.57	0.52	0.51
query10	0.56	0.54	0.55
query11	0.16	0.12	0.11
query12	0.16	0.12	0.12
query13	0.63	0.61	0.63
query14	0.99	0.99	0.98
query15	0.81	0.79	0.82
query16	0.40	0.42	0.39
query17	1.05	1.06	1.04
query18	0.24	0.22	0.22
query19	1.84	1.77	1.78
query20	0.02	0.02	0.01
query21	15.44	0.27	0.14
query22	5.01	0.05	0.04
query23	16.08	0.30	0.10
query24	1.15	0.28	0.62
query25	0.12	0.05	0.07
query26	0.14	0.13	0.13
query27	0.09	0.06	0.05
query28	4.35	1.21	1.02
query29	12.57	4.06	3.31
query30	0.28	0.14	0.12
query31	2.82	0.61	0.38
query32	3.22	0.56	0.46
query33	2.99	3.07	3.07
query34	16.83	5.21	4.50
query35	4.53	4.52	4.59
query36	0.69	0.51	0.49
query37	0.12	0.07	0.07
query38	0.08	0.04	0.04
query39	0.04	0.03	0.03
query40	0.17	0.14	0.14
query41	0.09	0.04	0.03
query42	0.05	0.03	0.03
query43	0.04	0.04	0.03
Total cold run time: 97.87 s
Total hot run time: 27.35 s

[hello-stephen]

FE Regression Coverage Report

Increment line coverage 0.00% (0/1) 🎉
Increment coverage report
Complete coverage report

[dataroaring]

LGTM