fix some comments for export column tables

[dorooleg]

Changelog entry

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Changelog category

• Not for changelog (changelog entry is not required)

Description for reviewers

comments: #28847 (review)

[github-actions]

🟢 2025-11-27 09:57:47 UTC The validation of the Pull Request description is successful.

[Copilot]

Pull request overview

This PR removes duplicate export-related files and applies code formatting improvements to function signatures in the export module. The duplicate files ydb/apps/ydbd/export.h and ydb/apps/ydbd/export.cpp are removed, as the actual implementation resides in the ydb/apps/ydbd/export/ subdirectory.

• Removes duplicate export.h and export.cpp files from the ydb/apps/ydbd/ directory
• Improves code formatting by splitting long function signatures across multiple lines in export_common.cpp
• Ensures the version with proper documentation comments is retained

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
ydb/core/tx/datashard/export_common.cpp	Reformats GenRowTableScheme and GenColumnTableScheme function signatures to improve readability by splitting them across multiple lines
ydb/apps/ydbd/export.h	Removes duplicate header file; the actual implementation exists in ydb/apps/ydbd/export/export.h
ydb/apps/ydbd/export.cpp	Removes duplicate implementation file; the actual implementation with proper comments exists in ydb/apps/ydbd/export/export.cpp

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[CyberROFL]

@dorooleg не собирается.

[github-actions]

⚪ 2025-11-27 16:29:46 UTC Pre-commit check linux-x86_64-release-asan for bf3fde6 has started.
⚪ 2025-11-27 16:30:04 UTC Artifacts will be uploaded here
⚪ 2025-11-27 16:32:14 UTC ya make is running...
🟡 2025-11-27 17:41:54 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?
11891	11763	0	111	7	10

🟢 2025-11-27 17:42:02 UTC Build successful.
🟢 2025-11-27 17:42:32 UTC ydbd size 3.8 GiB changed* by +480 Bytes, which is < 100.0 KiB vs main: OK

ydbd size dash	main: dc94702	merge: bf3fde6	diff	diff %
ydbd size	4 113 743 632 Bytes	4 113 744 112 Bytes	+480 Bytes	+0.000%
ydbd stripped size	1 528 667 440 Bytes	1 528 667 952 Bytes	+512 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]

⚪ 2025-11-27 16:31:31 UTC Pre-commit check linux-x86_64-relwithdebinfo for bf3fde6 has started.
⚪ 2025-11-27 16:31:48 UTC Artifacts will be uploaded here
⚪ 2025-11-27 16:34:00 UTC ya make is running...
🟡 2025-11-27 18:06:47 UTC Some tests failed, follow the links below. Going to retry failed tests...

Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
39499	36635	0	1	2841	22

⚪ 2025-11-27 18:06:59 UTC ya make is running... (failed tests rerun, try 2)
🟢 2025-11-27 18:17:21 UTC Tests successful.

Ya make output | Test bloat | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
43 (only retried tests)	28	0	0	0	15

🟢 2025-11-27 18:17:28 UTC Build successful.
🟢 2025-11-27 18:17:50 UTC ydbd size 2.3 GiB changed* by -2.4 KiB, which is <= 0 Bytes vs main: OK

ydbd size dash	main: c48120a	merge: bf3fde6	diff	diff %
ydbd size	2 457 675 712 Bytes	2 457 673 280 Bytes	-2.4 KiB	-0.000%
ydbd stripped size	523 640 488 Bytes	523 638 056 Bytes	-2.4 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}