branch-3.1: [fix](prepare statement)Prepare stage only explain sql to get output slots. #56224

[Jibing-Li]

backport: #56224

[Thearas]

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?

[Jibing-Li]

run buildall

[doris-robot]

TPC-H: Total hot run time: 34211 ms

machine: 'aliyun_ecs.c7a.8xlarge_32C64G'
scripts: https://github.com/apache/doris/tree/master/tools/tpch-tools
Tpch sf100 test result on commit 00cea8b081c17560a9facf2b8f5b4e4f33b78ae2, data reload: false

------ Round 1 ----------------------------------
q1	17668	5678	5424	5424
q2	2056	418	318	318
q3	12074	1330	790	790
q4	10283	904	525	525
q5	8884	2435	2238	2238
q6	203	170	137	137
q7	953	789	658	658
q8	9376	1558	1271	1271
q9	5369	4968	4987	4968
q10	6799	2336	1929	1929
q11	507	317	294	294
q12	384	386	238	238
q13	17791	3741	3174	3174
q14	250	250	230	230
q15	541	483	473	473
q16	476	469	419	419
q17	743	908	451	451
q18	7354	6656	6516	6516
q19	1228	1000	591	591
q20	394	394	246	246
q21	3552	2504	2303	2303
q22	1143	1089	1018	1018
Total cold run time: 108028 ms
Total hot run time: 34211 ms

----- Round 2, with runtime_filter_mode=off -----
q1	5555	5534	5592	5534
q2	280	350	245	245
q3	2377	2727	2426	2426
q4	1500	1934	1424	1424
q5	4693	5179	5139	5139
q6	186	177	131	131
q7	2199	2034	1883	1883
q8	2716	2914	2794	2794
q9	7391	7377	7413	7377
q10	2982	3383	2873	2873
q11	633	555	526	526
q12	734	860	684	684
q13	3607	3856	3289	3289
q14	317	315	293	293
q15	542	480	476	476
q16	469	529	464	464
q17	1334	1796	1288	1288
q18	8010	7585	7589	7585
q19	930	1119	1237	1119
q20	2127	2200	1965	1965
q21	5732	5251	4939	4939
q22	1158	1163	1064	1064
Total cold run time: 55472 ms
Total hot run time: 53518 ms

[doris-robot]

ClickBench: Total hot run time: 30.75 s

machine: 'aliyun_ecs.c7a.8xlarge_32C64G'
scripts: https://github.com/apache/doris/tree/master/tools/clickbench-tools
ClickBench test result on commit 00cea8b081c17560a9facf2b8f5b4e4f33b78ae2, data reload: false

query1	0.04	0.04	0.03
query2	0.08	0.03	0.04
query3	0.24	0.07	0.08
query4	1.60	0.11	0.11
query5	0.54	0.56	0.52
query6	1.13	0.74	0.74
query7	0.03	0.02	0.01
query8	0.04	0.04	0.05
query9	0.64	0.53	0.52
query10	0.59	0.61	0.58
query11	0.17	0.12	0.12
query12	0.16	0.12	0.13
query13	0.63	0.62	0.61
query14	0.82	0.81	0.81
query15	0.88	0.87	0.84
query16	0.42	0.42	0.40
query17	1.10	1.13	1.09
query18	0.27	0.25	0.25
query19	2.01	1.94	2.15
query20	0.02	0.01	0.01
query21	15.36	1.10	0.69
query22	0.74	0.86	0.75
query23	14.93	1.61	0.69
query24	3.35	1.17	1.24
query25	0.27	0.08	0.06
query26	0.30	0.17	0.16
query27	0.05	0.05	0.05
query28	13.78	1.13	0.48
query29	12.64	4.64	3.81
query30	0.27	0.10	0.08
query31	2.82	0.66	0.42
query32	3.26	0.58	0.49
query33	3.09	3.07	3.11
query34	16.74	5.20	4.57
query35	4.64	4.62	4.57
query36	0.67	0.53	0.50
query37	0.09	0.06	0.06
query38	0.05	0.04	0.04
query39	0.04	0.03	0.03
query40	0.18	0.15	0.13
query41	0.08	0.04	0.03
query42	0.04	0.03	0.04
query43	0.04	0.04	0.03
Total cold run time: 104.84 s
Total hot run time: 30.75 s

[Jibing-Li]

run feut

[hello-stephen]

FE UT Coverage Report

Increment line coverage 0.00% (0/7) 🎉
Increment coverage report
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