[WIP] pq/watermarks: avoid re-sending idleness notification

[yumkam]

Changelog entry

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Changelog category

• Not for changelog (changelog entry is not required)

Description for reviewers

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[github-actions]

🟢 2025-10-25 21:20:15 UTC The validation of the Pull Request description is successful.

[github-actions]

⚪ 2025-10-25 21:20:58 UTC Pre-commit check linux-x86_64-relwithdebinfo for 9064801 has started.
⚪ 2025-10-25 21:21:13 UTC Artifacts will be uploaded here
⚪ 2025-10-25 21:24:42 UTC ya make is running...
🟡 2025-10-25 22:55:14 UTC Some tests failed, follow the links below. Going to retry failed tests...

Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
38519	35722	0	7	2763	27

⚪ 2025-10-25 22:55:23 UTC ya make is running... (failed tests rerun, try 2)
🟡 2025-10-25 23:10:38 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?
459 (only retried tests)	440	0	1	0	18

⚪ 2025-10-25 23:10:41 UTC ya make is running... (failed tests rerun, try 3)
🟢 2025-10-25 23:23:26 UTC Tests successful.

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

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
416 (only retried tests)	397	0	0	0	19

🟢 2025-10-25 23:23:29 UTC Build successful.
🟢 2025-10-25 23:23:47 UTC ydbd size 2.3 GiB changed* by +19.7 KiB, which is < 100.0 KiB vs main: OK

ydbd size dash	main: 83fc358	merge: 9064801	diff	diff %
ydbd size	2 437 348 064 Bytes	2 437 368 256 Bytes	+19.7 KiB	+0.001%
ydbd stripped size	518 131 848 Bytes	518 135 816 Bytes	+3.9 KiB	+0.001%

^{*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]

⚪ 2025-10-25 21:21:01 UTC Pre-commit check linux-x86_64-release-asan for 9064801 has started.
⚪ 2025-10-25 21:21:15 UTC Artifacts will be uploaded here
⚪ 2025-10-25 21:24:17 UTC ya make is running...
🟡 2025-10-25 23:38:35 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?
15271	14715	0	253	284	19

🟢 2025-10-25 23:38:42 UTC Build successful.
🟢 2025-10-25 23:39:07 UTC ydbd size 3.8 GiB changed* by +35.5 KiB, which is < 100.0 KiB vs main: OK

ydbd size dash	main: 83fc358	merge: 9064801	diff	diff %
ydbd size	4 055 765 648 Bytes	4 055 802 032 Bytes	+35.5 KiB	+0.001%
ydbd stripped size	1 506 051 808 Bytes	1 506 065 344 Bytes	+13.2 KiB	+0.001%

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