Fixed processing kafka batch v0 with many messages

[nshestakov]

Changelog entry

Поправлена ошибка, когда при записи сообщений kafka , использующих формат батча v0 и v1 сохранялось только первое сообщение батча (все остальные игнорировались)

Changelog category

• Bugfix

Description for reviewers

LOGBROKER-9936
#24272

[github-actions]

🟢 2025-09-05 11:26:49 UTC The validation of the Pull Request description is successful.

[github-actions]

⚪ 2025-09-05 11:28:12 UTC Pre-commit check linux-x86_64-release-asan for f3f36d3 has started.
⚪ 2025-09-05 11:28:28 UTC Artifacts will be uploaded here
⚪ 2025-09-05 11:31:22 UTC ya make is running...
🟡 2025-09-05 12:44:24 UTC Some tests failed, follow the links below. This fail is not in blocking policy yet Going to retry failed tests...

Test history | Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
14433	14210	0	55	133	35

⚪ 2025-09-05 12:45:48 UTC ya make is running... (failed tests rerun, try 2)
🟡 2025-09-05 12:58:05 UTC Some tests failed, follow the links below. This fail is not in blocking policy yet Going to retry failed tests...

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

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
275 (only retried tests)	221	0	4	18	32

⚪ 2025-09-05 12:58:15 UTC ya make is running... (failed tests rerun, try 3)
🟡 2025-09-05 13:16:45 UTC Some tests failed, follow the links below. This fail is not in blocking policy yet

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

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
82 (only retried tests)	34	0	3	15	30

🟢 2025-09-05 13:16:55 UTC Build successful.
🟢 2025-09-05 13:17:19 UTC ydbd size 3.8 GiB changed* by +8.3 KiB, which is < 100.0 KiB vs stable-25-2-1: OK

ydbd size dash	stable-25-2-1: 1840c95	merge: f3f36d3	diff	diff %
ydbd size	4 045 397 736 Bytes	4 045 406 232 Bytes	+8.3 KiB	+0.000%
ydbd stripped size	1 408 430 264 Bytes	1 408 433 208 Bytes	+2.9 KiB	+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]

⚪ 2025-09-05 11:28:14 UTC Pre-commit check linux-x86_64-relwithdebinfo for f3f36d3 has started.
⚪ 2025-09-05 11:28:46 UTC Artifacts will be uploaded here
⚪ 2025-09-05 11:32:05 UTC ya make is running...
🟢 2025-09-05 12:24:14 UTC Tests successful.

Test history | Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
28616	27321	0	0	1243	52

🟢 2025-09-05 12:26:45 UTC Build successful.
🟢 2025-09-05 12:26:59 UTC ydbd size 2.2 GiB changed* by +4.2 KiB, which is < 100.0 KiB vs stable-25-2-1: OK

ydbd size dash	stable-25-2-1: 1840c95	merge: f3f36d3	diff	diff %
ydbd size	2 324 644 760 Bytes	2 324 649 080 Bytes	+4.2 KiB	+0.000%
ydbd stripped size	487 220 200 Bytes	487 221 032 Bytes	+832 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}