Properly rewrite log capturing (#17333)

[eivanov89]

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[github-actions]

⚪ 2025-06-11 14:54:24 UTC Pre-commit check linux-x86_64-release-asan for 1dd082d has started.
⚪ 2025-06-11 14:54:44 UTC Artifacts will be uploaded here
⚪ 2025-06-11 14:57:49 UTC ya make is running...
🟡 2025-06-11 15:39:36 UTC Some tests failed, follow the links below. This fail is not in blocking policy yet Going to retry failed tests...

Details

Test history | Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
1367	1292	0	13	56	6

⚪ 2025-06-11 15:39:52 UTC ya make is running... (failed tests rerun, try 2)
🟡 2025-06-11 16:02:57 UTC Some tests failed, follow the links below. This fail is not in blocking policy yet Going to retry failed tests...

Details

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

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
202 (only retried tests)	173	0	7	15	7

⚪ 2025-06-11 16:03:09 UTC ya make is running... (failed tests rerun, try 3)
🟡 2025-06-11 16:26:11 UTC Some tests failed, follow the links below. This fail is not in blocking policy yet

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

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
161 (only retried tests)	133	0	6	16	6

🟢 2025-06-11 16:26:20 UTC Build successful.
🟢 2025-06-11 16:26:38 UTC ydbd size 3.9 GiB changed* by +57.8 KiB, which is < 100.0 KiB vs main: OK

ydbd size dash	main: 516a269	merge: 1dd082d	diff	diff %
ydbd size	4 167 888 184 Bytes	4 167 947 368 Bytes	+57.8 KiB	+0.001%
ydbd stripped size	1 445 741 560 Bytes	1 445 762 296 Bytes	+20.2 KiB	+0.001%

^{*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]

⚪ 2025-06-11 14:55:54 UTC Pre-commit check linux-x86_64-relwithdebinfo for 1dd082d has started.
⚪ 2025-06-11 14:56:06 UTC Artifacts will be uploaded here
⚪ 2025-06-11 14:58:39 UTC ya make is running...
🟢 2025-06-11 15:19:18 UTC Tests successful.

Test history | Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
2139	2119	0	0	3	17

🟢 2025-06-11 15:19:36 UTC Build successful.
🟢 2025-06-11 15:19:47 UTC ydbd size 2.2 GiB changed* by +18.5 KiB, which is < 100.0 KiB vs main: OK

ydbd size dash	main: d53e819	merge: 1dd082d	diff	diff %
ydbd size	2 369 848 080 Bytes	2 369 867 000 Bytes	+18.5 KiB	+0.001%
ydbd stripped size	497 046 280 Bytes	497 050 888 Bytes	+4.5 KiB	+0.001%

^{*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]

🟢 2025-06-11 14:56:25 UTC The validation of the Pull Request description is successful.

[Copilot]

Pull Request Overview

This PR replaces the old TStdErrCapture approach with a new TLogBackendWithCapture for log collection, removes the deprecated stderr capture code, and integrates the new backend into TUI workflows. It also adds comprehensive unit tests for the new backend.

• Remove stderr_capture.* and add log_backend.*
• Update build files and code paths in runner.cpp and import.cpp to use TLogBackendWithCapture
• Add unit tests covering the new log capturing behavior

Reviewed Changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
ydb/library/workload/tpcc/ya.make	Added log_backend.cpp, removed stderr_capture.cpp
ydb/library/workload/tpcc/ut/ya.make	Added log_capture_ut.cpp to unit test build
ydb/library/workload/tpcc/ut/log_capture_ut.cpp	New tests for TLogBackendWithCapture
ydb/library/workload/tpcc/stderr_capture.h/.cpp	Removed obsolete stderr capture implementation
ydb/library/workload/tpcc/log_backend.h/.cpp	New TLogBackendWithCapture implementation
ydb/library/workload/tpcc/runner.cpp	Switched TUI log capture to use TLogBackendWithCapture
ydb/library/workload/tpcc/import.cpp	Switched import logic to use TLogBackendWithCapture

Comments suppressed due to low confidence (1)

ydb/library/workload/tpcc/log_backend.h:16

• [nitpick] The public interface of TLogBackendWithCapture lacks comments describing thread-safety guarantees and expected usage patterns. Adding brief doc comments for StartCapture, StopCapture, and GetLogLines would improve maintainability.

class TLogBackendWithCapture : public TLogBackend {