Fix LastOffset bug and some tests

[FloatingCrowbar]

• Fix key-comp+retention test
• Fix tests and LastOffset bug in PQ

Changelog entry

Fix bug in KastOffset and some tests

Changelog category

• Not for changelog (changelog entry is not required)

Description for reviewers

...

[github-actions]

🟢 2025-11-07 20:43:30 UTC The validation of the Pull Request description is successful.

[github-actions]

⚪ 2025-11-07 20:44:09 UTC Pre-commit check linux-x86_64-relwithdebinfo for 0a80353 has started.
⚪ 2025-11-07 20:44:28 UTC Artifacts will be uploaded here
⚪ 2025-11-07 20:46:52 UTC ya make is running...
🟡 2025-11-07 22:27:07 UTC Some tests failed, follow the links below. Going to retry failed tests...

Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
31592	30169	0	10	1386	27

⚪ 2025-11-07 22:27:28 UTC ya make is running... (failed tests rerun, try 2)
🟡 2025-11-07 22:35:48 UTC Some tests failed, follow the links below. Going to retry failed tests...

Ya make output | Test bloat | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
70 (only retried tests)	54	0	1	0	15

⚪ 2025-11-07 22:35:59 UTC ya make is running... (failed tests rerun, try 3)
🔴 2025-11-07 22:43:27 UTC Some tests failed, follow the links below.

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

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
32 (only retried tests)	16	0	1	0	15

🟢 2025-11-07 22:43:38 UTC Build successful.
🟢 2025-11-07 22:44:03 UTC ydbd size 2.3 GiB changed* by +16 Bytes, which is < 100.0 KiB vs main: OK

ydbd size dash	main: 06b1da6	merge: 0a80353	diff	diff %
ydbd size	2 431 922 720 Bytes	2 431 922 736 Bytes	+16 Bytes	+0.000%
ydbd stripped size	516 554 512 Bytes	516 554 512 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]

⚪ 2025-11-07 20:44:32 UTC Pre-commit check linux-x86_64-release-asan for 0a80353 has started.
⚪ 2025-11-07 20:44:50 UTC Artifacts will be uploaded here
⚪ 2025-11-07 20:47:11 UTC ya make is running...
🟡 2025-11-07 22:58:36 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?
15453	14904	0	237	286	26

🟢 2025-11-07 22:58:50 UTC Build successful.
🟢 2025-11-07 22:59:21 UTC ydbd size 3.8 GiB changed* by -16 Bytes, which is <= 0 Bytes vs main: OK

ydbd size dash	main: 06b1da6	merge: 0a80353	diff	diff %
ydbd size	4 073 198 008 Bytes	4 073 197 992 Bytes	-16 Bytes	-0.000%
ydbd stripped size	1 511 913 640 Bytes	1 511 913 576 Bytes	-64 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}