feat: allow __ydb_backup paths in backup collections

[Enjection]

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]

🟢 2025-10-22 11:33:48 UTC The validation of the Pull Request description is successful.

[CyberROFL]

@Enjection привяжи issue.

[github-actions]

⚪ 2025-10-27 10:11:44 UTC Pre-commit check linux-x86_64-relwithdebinfo for 40c1596 has started.
⚪ 2025-10-27 10:12:00 UTC Artifacts will be uploaded here
⚪ 2025-10-27 10:13:22 UTC ya make is running...
🟡 2025-10-27 11:51:04 UTC Some tests failed, follow the links below. Going to retry failed tests...

Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
39018	36220	0	6	2765	27

⚪ 2025-10-27 11:51:15 UTC ya make is running... (failed tests rerun, try 2)
🟡 2025-10-27 12:17:41 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?
841 (only retried tests)	813	0	4	2	22

⚪ 2025-10-27 12:17:44 UTC ya make is running... (failed tests rerun, try 3)
🟢 2025-10-27 12:38:34 UTC Tests successful.

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

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
670 (only retried tests)	653	0	0	0	17

🟢 2025-10-27 12:38:37 UTC Build successful.
🟢 2025-10-27 12:38:56 UTC ydbd size 2.3 GiB changed* by +9.8 KiB, which is < 100.0 KiB vs main: OK

ydbd size dash	main: e569a87	merge: 40c1596	diff	diff %
ydbd size	2 436 863 248 Bytes	2 436 873 280 Bytes	+9.8 KiB	+0.000%
ydbd stripped size	518 032 264 Bytes	518 034 120 Bytes	+1.8 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}

[github-actions]

⚪ 2025-10-27 10:14:49 UTC Pre-commit check linux-x86_64-release-asan for 40c1596 has started.
⚪ 2025-10-27 10:15:04 UTC Artifacts will be uploaded here
⚪ 2025-10-27 10:16:27 UTC ya make is running...
🟡 2025-10-27 12:24:52 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?
15480	15007	0	186	266	21

🟢 2025-10-27 12:24:58 UTC Build successful.
🟢 2025-10-27 12:25:21 UTC ydbd size 3.8 GiB changed* by +17.5 KiB, which is < 100.0 KiB vs main: OK

ydbd size dash	main: e569a87	merge: 40c1596	diff	diff %
ydbd size	4 054 993 520 Bytes	4 055 011 456 Bytes	+17.5 KiB	+0.000%
ydbd stripped size	1 505 745 344 Bytes	1 505 752 512 Bytes	+7.0 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}