25-3-1: Fix successful reads not always waiting for read conflicts to persist

[snaury]

Changelog entry

Fix successful reads not always waiting for read conflicts to persist, which could cause commits to violate serializability. Fixes #27961.

Changelog category

• Bugfix

Description for reviewers

Merge #27963.

[github-actions]

🟢 2025-10-31 07:59:48 UTC The validation of the Pull Request description is successful.

[github-actions]

⚪ 2025-10-31 08:00:06 UTC Pre-commit check linux-x86_64-release-asan for 69f664b has started.
⚪ 2025-10-31 08:00:20 UTC Artifacts will be uploaded here
⚪ 2025-10-31 08:03:52 UTC ya make is running...
🟡 2025-10-31 10:07:21 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?
15611	15087	0	179	327	18

🟢 2025-10-31 10:08:37 UTC Build successful.
🟢 2025-10-31 10:09:00 UTC ydbd size 3.8 GiB changed* by +48 Bytes, which is < 100.0 KiB vs stable-25-3-1: OK

ydbd size dash	stable-25-3-1: 724c275	merge: 69f664b	diff	diff %
ydbd size	4 052 606 368 Bytes	4 052 606 416 Bytes	+48 Bytes	+0.000%
ydbd stripped size	1 510 399 232 Bytes	1 510 399 232 Bytes	0 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]

⚪ 2025-10-31 08:00:18 UTC Pre-commit check linux-x86_64-relwithdebinfo for 69f664b has started.
⚪ 2025-10-31 08:00:32 UTC Artifacts will be uploaded here
⚪ 2025-10-31 08:04:02 UTC ya make is running...
🟡 2025-10-31 09:33:51 UTC Some tests failed, follow the links below. Going to retry failed tests...

Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
38277	35567	0	10	2673	27

⚪ 2025-10-31 09:37:04 UTC ya make is running... (failed tests rerun, try 2)
🟢 2025-10-31 09:55:03 UTC Tests successful.

Ya make output | Test bloat | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
1129 (only retried tests)	1110	0	0	1	18

🟢 2025-10-31 09:55:13 UTC Build successful.
🟢 2025-10-31 09:55:29 UTC ydbd size 2.3 GiB changed* by +16 Bytes, which is < 100.0 KiB vs stable-25-3-1: OK

ydbd size dash	stable-25-3-1: 724c275	merge: 69f664b	diff	diff %
ydbd size	2 435 468 480 Bytes	2 435 468 496 Bytes	+16 Bytes	+0.000%
ydbd stripped size	521 563 016 Bytes	521 563 016 Bytes	0 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}