fix: Skip val_check_interval validation when limit_val_batches=0 (#21560)

* fix: Skip val_check_interval validation when limit_val_batches=0

When limit_val_batches=0 (validation disabled), the val_check_interval
sanity check is now skipped since validation will not run anyway.

Fixes #21553

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* Move comments inside if-elif block per review feedback

* Remove extra blank line in test docstring

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* Apply suggestion from @deependujha

* Apply suggestion from @deependujha

* Add changelog entry for val_check_interval fix

* Collapse test docstring to single line

* Add co-author credit for issue reporter

Co-authored-by: Taha Yassine <40228615+taha-yassine@users.noreply.github.com>

* update

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Deependu <deependujha21@gmail.com>
Co-authored-by: Taha Yassine <40228615+taha-yassine@users.noreply.github.com>