[25-3-1] Fix snapshot cleanup on ModifyScheme failures during vector index build (#27454)

[vitalif]

Changelog category

• Not for changelog (changelog entry is not required)

Description for reviewers

Cherry-pick of #27581

[github-actions]

🟢 2025-10-27 10:47:30 UTC The validation of the Pull Request description is successful.

[github-actions]

⚪ 2025-10-27 13:23:40 UTC Pre-commit check linux-x86_64-relwithdebinfo for 3c869ad has started.
⚪ 2025-10-27 13:23:54 UTC Artifacts will be uploaded here
⚪ 2025-10-27 13:27:38 UTC ya make is running...
🟡 2025-10-27 15:06:53 UTC Some tests failed, follow the links below. Going to retry failed tests...

Details

Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
38251	35556	0	10	2651	34

⚪ 2025-10-27 15:10:01 UTC ya make is running... (failed tests rerun, try 2)
🟡 2025-10-27 15:34:45 UTC Some tests failed, follow the links below. Going to retry failed tests...

Details

Ya make output | Test bloat | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
752 (only retried tests)	727	0	3	1	21

⚪ 2025-10-27 15:34:56 UTC ya make is running... (failed tests rerun, try 3)
🟢 2025-10-27 15:55:29 UTC Tests successful.

Ya make output | Test bloat | Test bloat | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
532 (only retried tests)	518	0	0	0	14

🟢 2025-10-27 15:55:38 UTC Build successful.
🟢 2025-10-27 15:55:53 UTC ydbd size 2.3 GiB changed* by +472 Bytes, which is < 100.0 KiB vs stable-25-3-1: OK

ydbd size dash	stable-25-3-1: 4618ed6	merge: 3c869ad	diff	diff %
ydbd size	2 432 909 192 Bytes	2 432 909 664 Bytes	+472 Bytes	+0.000%
ydbd stripped size	521 159 272 Bytes	521 159 400 Bytes	+128 Bytes	+0.000%

^{*please be aware that the difference is based on comparing your commit and the last completed build from the post-commit, check comparation}

[github-actions]

⚪ 2025-10-27 10:49:32 UTC Pre-commit check linux-x86_64-release-asan for 3c869ad has started.
⚪ 2025-10-27 10:49:46 UTC Artifacts will be uploaded here
⚪ 2025-10-27 10:53:20 UTC ya make is running...
🟡 2025-10-27 13:12:08 UTC Some tests failed, follow the links below. This fail is not in blocking policy yet

Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
15587	15025	0	228	317	17

🟢 2025-10-27 13:13:27 UTC Build successful.
🟢 2025-10-27 13:13:50 UTC ydbd size 3.8 GiB changed* by +816 Bytes, which is < 100.0 KiB vs stable-25-3-1: OK

ydbd size dash	stable-25-3-1: 4618ed6	merge: 3c869ad	diff	diff %
ydbd size	4 047 881 984 Bytes	4 047 882 800 Bytes	+816 Bytes	+0.000%
ydbd stripped size	1 507 918 560 Bytes	1 507 918 912 Bytes	+352 Bytes	+0.000%

^{*please be aware that the difference is based on comparing your commit and the last completed build from the post-commit, check comparation}