stable-25-3: cherry pick PR 27297, PR 28613, PR 29360, PR 29466

[rosik]

Cherry-pick:

• Add compatibility test for InferPDiskSlotCount feature #27297
• Fix segfault when handling ChangeGroupSizeInUnits during VDisk LocalRecovery #28613
• Fix flaky test_pdisk_slot_size_in_units.py #29360
• Fix ydb/tests to conform py2 syntax #29466

[github-actions]

🟢 2025-11-24 16:36:41 UTC The validation of the Pull Request description is successful.

[github-actions]

⚪ 2025-11-24 16:32:06 UTC Pre-commit check linux-x86_64-release-asan for c599a6f has started.
⚪ 2025-11-24 16:32:22 UTC Artifacts will be uploaded here
⚪ 2025-11-24 16:36:11 UTC ya make is running...
🟡 2025-11-24 19:07:19 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?
16215	15674	0	204	314	23

🟢 2025-11-24 19:08:37 UTC Build successful.
🟢 2025-11-24 19:09:03 UTC ydbd size 3.8 GiB changed* by +2.4 KiB, which is < 100.0 KiB vs stable-25-3: OK

ydbd size dash	stable-25-3: 0dcb1c2	merge: c599a6f	diff	diff %
ydbd size	4 064 676 280 Bytes	4 064 678 712 Bytes	+2.4 KiB	+0.000%
ydbd stripped size	1 514 525 152 Bytes	1 514 526 304 Bytes	+1.1 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]

⚪ 2025-11-24 16:33:14 UTC Pre-commit check linux-x86_64-relwithdebinfo for c599a6f has started.
⚪ 2025-11-24 16:33:29 UTC Artifacts will be uploaded here
⚪ 2025-11-24 16:37:07 UTC ya make is running...
🟡 2025-11-24 18:30:25 UTC Some tests failed, follow the links below. Going to retry failed tests...

Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
39111	36434	0	8	2650	19

⚪ 2025-11-24 18:33:55 UTC ya make is running... (failed tests rerun, try 2)
🟡 2025-11-24 18:48:11 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?
559 (only retried tests)	540	0	1	0	18

⚪ 2025-11-24 18:48:22 UTC ya make is running... (failed tests rerun, try 3)
🟢 2025-11-24 19:03:19 UTC Tests successful.

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

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
543 (only retried tests)	526	0	0	0	17

🟢 2025-11-24 19:03:29 UTC Build successful.
🟢 2025-11-24 19:03:53 UTC ydbd size 2.3 GiB changed* by +52.8 KiB, which is < 100.0 KiB vs stable-25-3: OK

ydbd size dash	stable-25-3: f6654c0	merge: c599a6f	diff	diff %
ydbd size	2 441 970 304 Bytes	2 442 024 384 Bytes	+52.8 KiB	+0.002%
ydbd stripped size	522 701 224 Bytes	522 710 056 Bytes	+8.6 KiB	+0.002%

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