[25-3-1] Handle new prefixes in prefixed vector index update

[vitalif]

Changelog category

• Not for changelog (changelog entry is not required)

Description for reviewers

Cherry-pick of #25991, #26046, #26120, #25505, #26613, #26614

[github-actions]

🟢 2025-11-01 10:15:17 UTC The validation of the Pull Request description is successful.

[github-actions]

⚪ 2025-11-01 10:16:08 UTC Pre-commit check linux-x86_64-release-asan for 79b0eed has started.
⚪ 2025-11-01 10:16:23 UTC Artifacts will be uploaded here
⚪ 2025-11-01 10:20:07 UTC ya make is running...
🔴 2025-11-01 10:31:15 UTC Build failed, see the logs. Also see fail summary

[github-actions]

⚪ 2025-11-01 10:18:24 UTC Pre-commit check linux-x86_64-relwithdebinfo for 79b0eed has started.
⚪ 2025-11-01 10:18:38 UTC Artifacts will be uploaded here
⚪ 2025-11-01 10:22:22 UTC ya make is running...
🔴 2025-11-01 10:29:43 UTC Build failed, see the logs. Also see fail summary

[github-actions]

⚪ 2025-11-01 10:42:23 UTC Pre-commit check linux-x86_64-relwithdebinfo for 7ce1cce has started.
⚪ 2025-11-01 10:42:38 UTC Artifacts will be uploaded here
⚪ 2025-11-01 10:46:40 UTC ya make is running...
🟡 2025-11-01 12:38:20 UTC Some tests failed, follow the links below. Going to retry failed tests...

Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
40255	37577	0	6	2651	21

⚪ 2025-11-01 12:41:33 UTC ya make is running... (failed tests rerun, try 2)
🟢 2025-11-01 12:59:28 UTC Tests successful.

Ya make output | Test bloat | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
730 (only retried tests)	711	0	0	1	18

🟢 2025-11-01 12:59:37 UTC Build successful.
🟡 2025-11-01 12:59:52 UTC ydbd size 2.3 GiB changed* by +1.7 MiB, which is >= 100.0 KiB vs stable-25-3-1: Warning

ydbd size dash	stable-25-3-1: f75c208	merge: 7ce1cce	diff	diff %
ydbd size	2 435 621 064 Bytes	2 437 436 856 Bytes	+1.7 MiB	+0.075%
ydbd stripped size	521 595 368 Bytes	521 925 288 Bytes	+322.2 KiB	+0.063%

^{*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]

⚪ 2025-11-01 10:42:36 UTC Pre-commit check linux-x86_64-release-asan for 7ce1cce has started.
⚪ 2025-11-01 10:42:50 UTC Artifacts will be uploaded here
⚪ 2025-11-01 10:46:43 UTC ya make is running...
🟡 2025-11-01 13:09:56 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?
17577	17047	0	191	316	23

🟢 2025-11-01 13:11:22 UTC Build successful.
🔴 2025-11-01 13:11:46 UTC ydbd size 3.8 GiB changed* by +4.1 MiB, which is >= 2.0 MiB vs stable-25-3-1: Alert

ydbd size dash	stable-25-3-1: f75c208	merge: 7ce1cce	diff	diff %
ydbd size	4 052 847 752 Bytes	4 057 121 264 Bytes	+4.1 MiB	+0.105%
ydbd stripped size	1 510 484 416 Bytes	1 512 155 712 Bytes	+1.6 MiB	+0.111%

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