deprioritise system tablets in balancer (#6840)

[vporyadke]

Changelog entry

make less coordinator&mediator moves

Changelog category

• Performance improvement

Additional information

backport of #6840

[github-actions]

⚪ 2024-07-24 12:59:43 UTC Pre-commit check for f6ea843 has started.
⚪ 2024-07-24 13:02:26 UTC Build linux-x86_64-release-asan is running...
🟢 2024-07-24 13:39:54 UTC Build successful.
⚪ 2024-07-24 13:40:11 UTC Tests are running...
🔴 2024-07-24 15:39:07 UTC Some tests failed, follow the links below.

Test history | Test log

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
11242	10664	0	86	320	172

🟢 2024-07-24 15:39:52 UTC ydbd size 5.2 GiB changed* by +26.4 KiB, which is < 100.0 KiB vs stable-24-3: OK

ydbd size dash	stable-24-3: bf5f3d7	merge: f6ea843	diff	diff %
ydbd size	5 616 909 560 Bytes	5 616 936 576 Bytes	+26.4 KiB	+0.000%
ydbd stripped size	1 211 406 792 Bytes	1 211 413 768 Bytes	+6.8 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]

⚪ 2024-07-24 13:00:50 UTC Pre-commit check for f6ea843 has started.
⚪ 2024-07-24 13:03:42 UTC Build linux-x86_64-release-clang14 is running...
🟢 2024-07-24 13:35:49 UTC Build successful.

[github-actions]

⚪ 2024-07-24 13:02:53 UTC Pre-commit check for f6ea843 has started.
⚪ 2024-07-24 13:05:36 UTC Build linux-x86_64-relwithdebinfo is running...
🟢 2024-07-24 13:59:12 UTC Build successful.
⚪ 2024-07-24 13:59:36 UTC Tests are running...
🔴 2024-07-24 15:41:38 UTC Some tests failed, follow the links below.

Test history | Test log

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
39758	34525	0	1	5221	11

🟢 2024-07-24 15:42:22 UTC ydbd size 8.1 GiB changed* by +20.9 KiB, which is < 100.0 KiB vs stable-24-3: OK

ydbd size dash	stable-24-3: bf5f3d7	merge: f6ea843	diff	diff %
ydbd size	8 727 584 672 Bytes	8 727 606 120 Bytes	+20.9 KiB	+0.000%
ydbd stripped size	477 316 552 Bytes	477 317 704 Bytes	+1.1 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}