[Fix](statistics)Fix analyze olap table couldn't get partition names bug.

[Jibing-Li]

Fix bug introduced by #24154
Call getPartitionNames to get all partitions while analyzing for olap table. Couldn't return NULL, otherwise analyze for olap table will do nothing.

Further comments

If this is a relatively large or complex change, kick off the discussion at dev@doris.apache.org by explaining why you chose the solution you did and what alternatives you considered, etc...

[Jibing-Li]

run buildall

[Kikyou1997]

Add some regression test or unit test to cover this problem?

[doris-robot]

(From new machine)TeamCity pipeline, clickbench performance test result:
the sum of best hot time: 46.85 seconds
stream load tsv: 616 seconds loaded 74807831229 Bytes, about 115 MB/s
stream load json: 21 seconds loaded 2358488459 Bytes, about 107 MB/s
stream load orc: 64 seconds loaded 1101869774 Bytes, about 16 MB/s
stream load parquet: 32 seconds loaded 861443392 Bytes, about 25 MB/s
insert into select: 29.7 seconds inserted 10000000 Rows, about 336K ops/s
storage size: 17162445680 Bytes

[Jibing-Li]

Add some regression test or unit test to cover this problem?

Added

[Jibing-Li]

run buildall

[doris-robot]

(From new machine)TeamCity pipeline, clickbench performance test result:
the sum of best hot time: 45.18 seconds
stream load tsv: 615 seconds loaded 74807831229 Bytes, about 116 MB/s
stream load json: 23 seconds loaded 2358488459 Bytes, about 97 MB/s
stream load orc: 64 seconds loaded 1101869774 Bytes, about 16 MB/s
stream load parquet: 32 seconds loaded 861443392 Bytes, about 25 MB/s
insert into select: 28.9 seconds inserted 10000000 Rows, about 346K ops/s
storage size: 17162353642 Bytes

[morningman]

lgtm

[github-actions]

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

[github-actions]

PR approved by anyone and no changes requested.