Add TRUNCATE TABLE implementation for tables with vector indexes

[flown4qqqq]

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Description for reviewers

This PR adds the ability to run TRUNCATE TABLE on tables that have global vector index and prefix vector index.

[github-actions]

⚪ 2026-01-28 17:08:04 UTC Pre-commit check linux-x86_64-relwithdebinfo for 47c68c9 has started.
⚫ 2026-01-28 17:08:28 UTC Check cancelled

[ydbot]

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[github-actions]

🟢 2026-01-28 17:09:17 UTC The validation of the Pull Request description is successful.

[github-actions]

⚪ 2026-01-28 17:10:38 UTC Pre-commit check linux-x86_64-relwithdebinfo for d47768b has started.
⚪ 2026-01-28 17:10:59 UTC Artifacts will be uploaded here
⚪ 2026-01-28 17:13:18 UTC ya make is running...
🟡 2026-01-28 19:14:22 UTC Some tests failed, follow the links below. Going to retry failed tests...

Details

Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
44947	41839	0	25	3044	39

⚪ 2026-01-28 19:14:40 UTC ya make is running... (failed tests rerun, try 2)
🟢 2026-01-28 19:20:47 UTC Tests successful.

Ya make output | Test bloat | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
622 (only retried tests)	605	0	0	3	14

🟢 2026-01-28 19:20:54 UTC Build successful.
🟢 2026-01-28 19:21:18 UTC ydbd size 2.4 GiB changed* by +6.0 KiB, which is < 100.0 KiB vs main: OK

ydbd size dash	main: 93cceb9	merge: d47768b	diff	diff %
ydbd size	2 527 426 160 Bytes	2 527 432 304 Bytes	+6.0 KiB	+0.000%
ydbd stripped size	536 258 088 Bytes	536 259 496 Bytes	+1.4 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]

⚪ 2026-01-28 17:13:17 UTC Pre-commit check linux-x86_64-release-asan for d47768b has started.
⚪ 2026-01-28 17:13:39 UTC Artifacts will be uploaded here
⚪ 2026-01-28 17:15:57 UTC ya make is running...
🟡 2026-01-28 18:32:08 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?
14354	14248	0	69	9	28

🟢 2026-01-28 18:32:18 UTC Build successful.
🟢 2026-01-28 18:32:48 UTC ydbd size 3.9 GiB changed* by +11.1 KiB, which is < 100.0 KiB vs main: OK

ydbd size dash	main: 93cceb9	merge: d47768b	diff	diff %
ydbd size	4 156 472 856 Bytes	4 156 484 192 Bytes	+11.1 KiB	+0.000%
ydbd stripped size	1 554 794 160 Bytes	1 554 800 688 Bytes	+6.4 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}

[vitalif]

в принципе всё норм, вот только не хотелось бы по numberOfChildren ориентироваться. вдруг в будущем ещё какая таблица появится? проверь плз по числу индексных полей, если поле одно то это глобальный индекс, если > 1 то префиксный