Merge secrets fixes to stable-25-3-1

[yurikiselev]

Changelog category

• Not for changelog (changelog entry is not required)

Description for reviewers

Правки в новые схемные секреты, которые отключены по дефолту флагом EnableSchemaSecrets. В 25-3 они уже заехали: поддержаны схемные объекты для секретов, SQL-синтаксис работы с ними, использование в федеративных запросах, которым нужен один секрет, и пр.
Тут доливаются доработки, чтобы секреты могли использоваться в запросах с несколькими секретами и разные доработки в новом локальном сервисе секретов, который отключен по дефолту.

[github-actions]

🟢 2025-10-11 05:54:01 UTC The validation of the Pull Request description is successful.

[github-actions]

⚪ 2025-10-13 06:39:45 UTC Pre-commit check linux-x86_64-relwithdebinfo for 85aa3a0 has started.
⚪ 2025-10-13 06:39:59 UTC Artifacts will be uploaded here
⚪ 2025-10-13 06:44:01 UTC ya make is running...

[github-actions]

⚪ 2025-10-11 05:55:00 UTC Pre-commit check linux-x86_64-release-asan for 85aa3a0 has started.
⚪ 2025-10-11 05:55:14 UTC Artifacts will be uploaded here
⚪ 2025-10-11 06:26:15 UTC ya make is running...
🟡 2025-10-11 08:45:40 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?
17507	16981	0	188	316	22

🟢 2025-10-11 08:47:06 UTC Build successful.
🟡 2025-10-11 08:47:29 UTC ydbd size 3.8 GiB changed* by +177.3 KiB, which is >= 100.0 KiB vs stable-25-3-1: Warning

ydbd size dash	stable-25-3-1: 77742af	merge: 85aa3a0	diff	diff %
ydbd size	4 046 035 016 Bytes	4 046 216 600 Bytes	+177.3 KiB	+0.004%
ydbd stripped size	1 507 272 960 Bytes	1 507 332 096 Bytes	+57.8 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}