25-3-1: make storage balancer async

[vporyadke]

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]

🟢 2025-11-21 16:56:02 UTC The validation of the Pull Request description is successful.

[github-actions]

⚪ 2025-11-19 23:21:32 UTC Pre-commit check linux-x86_64-release-asan for 94ae5e7 has started.
⚪ 2025-11-19 23:21:48 UTC Artifacts will be uploaded here
⚪ 2025-11-19 23:25:38 UTC ya make is running...
🟡 2025-11-20 01:31:12 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?
15616	15132	0	204	261	19

🟢 2025-11-20 01:32:27 UTC Build successful.
🟢 2025-11-20 01:32:52 UTC ydbd size 3.8 GiB changed* by +160 Bytes, which is < 100.0 KiB vs stable-25-3-1: OK

ydbd size dash	stable-25-3-1: 0f345d3	merge: 94ae5e7	diff	diff %
ydbd size	4 054 124 960 Bytes	4 054 125 120 Bytes	+160 Bytes	+0.000%
ydbd stripped size	1 510 965 472 Bytes	1 510 965 536 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}

[github-actions]

⚪ 2025-11-19 23:27:00 UTC Pre-commit check linux-x86_64-relwithdebinfo for 94ae5e7 has started.
⚪ 2025-11-19 23:27:06 UTC Artifacts will be uploaded here
⚪ 2025-11-19 23:30:37 UTC ya make is running...
🟡 2025-11-20 01:09:32 UTC Some tests failed, follow the links below. Going to retry failed tests...

Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
38294	35601	0	12	2656	25

⚪ 2025-11-20 01:12:36 UTC ya make is running... (failed tests rerun, try 2)
🟡 2025-11-20 01:32:31 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?
1033 (only retried tests)	1007	0	3	6	17

⚪ 2025-11-20 01:32:43 UTC ya make is running... (failed tests rerun, try 3)
🟢 2025-11-20 01:47:14 UTC Tests successful.

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

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
678 (only retried tests)	667	0	0	1	10

🟢 2025-11-20 01:47:22 UTC Build successful.
🟢 2025-11-20 01:47:41 UTC ydbd size 2.3 GiB changed* by +96 Bytes, which is < 100.0 KiB vs stable-25-3-1: OK

ydbd size dash	stable-25-3-1: 0f345d3	merge: 94ae5e7	diff	diff %
ydbd size	2 436 347 232 Bytes	2 436 347 328 Bytes	+96 Bytes	+0.000%
ydbd stripped size	521 740 456 Bytes	521 740 456 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}