Do not suggest NOT NULL in ydb import file csv

[pnv1]

Changelog entry

...

Changelog category

• Improvement

Description for reviewers

...

[github-actions]

🔴 2025-03-05 08:21:58 UTC The validation of the Pull Request description has failed. Please update the description.

The changelog entry is less than 20 characters or missing.

[github-actions]

⚪ 2025-03-05 08:24:20 UTC Pre-commit check linux-x86_64-relwithdebinfo for fbfcd8b has started.
⚪ 2025-03-05 08:24:35 UTC Artifacts will be uploaded here
⚪ 2025-03-05 08:26:56 UTC ya make is running...
🟢 2025-03-05 08:39:56 UTC Tests successful.

Test history | Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
1019	1008	0	0	4	7

🟢 2025-03-05 08:40:09 UTC Build successful.
🟢 2025-03-05 08:40:21 UTC ydbd size 2.1 GiB changed* by 0 Bytes, which is <= 0 Bytes vs main: OK

ydbd size dash	main: b0f9318	merge: fbfcd8b	diff	diff %
ydbd size	2 290 087 392 Bytes	2 290 087 392 Bytes	0 Bytes	0.000%
ydbd stripped size	479 952 320 Bytes	479 952 320 Bytes	0 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]

⚪ 2025-03-05 08:25:03 UTC Pre-commit check linux-x86_64-release-asan for fbfcd8b has started.
⚪ 2025-03-05 08:25:18 UTC Artifacts will be uploaded here
⚪ 2025-03-05 08:27:34 UTC ya make is running...
🟢 2025-03-05 08:40:40 UTC Tests successful.

Test history | Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
600	590	0	0	3	7

🟢 2025-03-05 08:40:50 UTC Build successful.
🟢 2025-03-05 08:41:04 UTC ydbd size 3.7 GiB changed* by -96 Bytes, which is <= 0 Bytes vs main: OK

ydbd size dash	main: b0f9318	merge: fbfcd8b	diff	diff %
ydbd size	3 990 870 208 Bytes	3 990 870 112 Bytes	-96 Bytes	-0.000%
ydbd stripped size	1 388 995 016 Bytes	1 388 994 952 Bytes	-64 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}