fix race between switch drain and node status

[vporyadke]

Changelog entry

...

Changelog category

• Not for changelog (changelog entry is not required)

Description for reviewers

Получалось два запуска дрейна, если TEvStatus прилетал между Execute и Complete у TxSwitchDrainOn. Лечится переносом запуска дрейна в Execute (когда-то раньше так и было, потом я в какой-то момент решил, что типа логичнее запуски иметь в Complete - ну и зря).

[github-actions]

⚪ 2025-10-16 09:47:40 UTC Pre-commit check linux-x86_64-relwithdebinfo for 38efd9f has started.
⚪ 2025-10-16 09:50:13 UTC Artifacts will be uploaded here
⚪ 2025-10-16 09:54:27 UTC ya make is running...
🟡 2025-10-16 11:41:29 UTC Some tests failed, follow the links below. Going to retry failed tests...

Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
38946	36162	0	2	2754	28

⚪ 2025-10-16 11:41:39 UTC ya make is running... (failed tests rerun, try 2)
🟢 2025-10-16 12:05:32 UTC Tests successful.

Ya make output | Test bloat | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
623 (only retried tests)	601	0	0	1	21

🟢 2025-10-16 12:05:35 UTC Build successful.
🟢 2025-10-16 12:05:52 UTC ydbd size 2.3 GiB changed* by -304 Bytes, which is <= 0 Bytes vs main: OK

ydbd size dash	main: 2dade7c	merge: 38efd9f	diff	diff %
ydbd size	2 424 167 608 Bytes	2 424 167 304 Bytes	-304 Bytes	-0.000%
ydbd stripped size	516 061 640 Bytes	516 061 512 Bytes	-128 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]

🟢 2025-10-16 14:32:35 UTC The validation of the Pull Request description is successful.

[github-actions]

⚪ 2025-10-16 09:49:09 UTC Pre-commit check linux-x86_64-release-asan for 38efd9f has started.
⚪ 2025-10-16 09:49:24 UTC Artifacts will be uploaded here
⚪ 2025-10-16 09:53:00 UTC ya make is running...
🟡 2025-10-16 12:13:27 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?
15783	15396	0	156	215	16

🟢 2025-10-16 12:13:32 UTC Build successful.
🟡 2025-10-16 12:13:55 UTC ydbd size 3.8 GiB changed* by +177.3 KiB, which is >= 100.0 KiB vs main: Warning

ydbd size dash	main: e1f3ac8	merge: 38efd9f	diff	diff %
ydbd size	4 033 075 488 Bytes	4 033 257 040 Bytes	+177.3 KiB	+0.005%
ydbd stripped size	1 497 937 632 Bytes	1 497 996 448 Bytes	+57.4 KiB	+0.004%

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

[CyberROFL]

@vporyadke нужно портировать в релевантные ветки.