Relax unnecessary checks for TKqpLocks proto fields

[snaury]

Changelog entry

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Description for reviewers

We historically used SendingShards/ReceivingShards in TKqpLocks for exchanging lock validation results. However, it has long been repurposed for generic commit/abort decision exchange. Now that we have operations (EvWrite with INSERT) which may fail due to constraint violation unrelated to locks, checking that SendingShards must have a lock is harmful. Relax these checks and decouple locks from sending/receiving shards. Now locks listed in the proto are always validated when present on commit (even when shard is not in the sending set for some reason), and readsets are always sent from shards in SendingShards.

This relaxation is safe to perform since current stable versions crash when encountering such data, and this patch doesn't change behavior otherwise. Intended for backporting into current stable versions.

Related to #19525.

[github-actions]

🟢 2025-07-10 09:10:32 UTC The validation of the Pull Request description is successful.

[github-actions]

⚪ 2025-07-10 09:06:00 UTC Pre-commit check linux-x86_64-relwithdebinfo for 7bcafed has started.
⚪ 2025-07-10 09:06:13 UTC Artifacts will be uploaded here
⚪ 2025-07-10 09:09:36 UTC ya make is running...
🟡 2025-07-10 10:21:09 UTC Some tests failed, follow the links below. Going to retry failed tests...

Test history | Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
29702	28278	0	7	1370	47

⚪ 2025-07-10 10:23:47 UTC ya make is running... (failed tests rerun, try 2)
🟢 2025-07-10 10:38:08 UTC Tests successful.

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

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
403 (only retried tests)	360	0	0	7	36

🟢 2025-07-10 10:38:17 UTC Build successful.
🟢 2025-07-10 10:38:39 UTC ydbd size 2.2 GiB changed* by -848 Bytes, which is <= 0 Bytes vs main: OK

ydbd size dash	main: 966f177	merge: 7bcafed	diff	diff %
ydbd size	2 391 010 200 Bytes	2 391 009 352 Bytes	-848 Bytes	-0.000%
ydbd stripped size	500 108 328 Bytes	500 108 072 Bytes	-256 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]

⚪ 2025-07-10 09:06:02 UTC Pre-commit check linux-x86_64-release-asan for 7bcafed has started.
⚪ 2025-07-10 09:06:15 UTC Artifacts will be uploaded here
⚪ 2025-07-10 09:09:26 UTC ya make is running...
🟡 2025-07-10 10:47:05 UTC Some tests failed, follow the links below. This fail is not in blocking policy yet

Test history | Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
14310	13865	0	225	197	23

🟢 2025-07-10 10:48:21 UTC Build successful.
🟢 2025-07-10 10:48:51 UTC ydbd size 3.9 GiB changed* by -4.8 KiB, which is <= 0 Bytes vs main: OK

ydbd size dash	main: 966f177	merge: 7bcafed	diff	diff %
ydbd size	4 204 566 072 Bytes	4 204 561 160 Bytes	-4.8 KiB	-0.000%
ydbd stripped size	1 456 365 720 Bytes	1 456 364 120 Bytes	-1.6 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}