Gallery: Minor code quality update

[ntsekouras]

What?

Minor update to address @felixarntz review here: https://github.com/WordPress/wordpress-develop/pull/3914/files#r1095179123

Testing Instructions

1. Gallery block should work as before.

[github-actions]

Flaky tests detected in 2c82685.
Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

🔍 Workflow run URL: https://github.com/WordPress/gutenberg/actions/runs/4102422216
📝 Reported issues:

• [Flaky Test] should always expand single line selection #39787 in specs/editor/various/multi-block-selection.test.js
• [Flaky Test] should be able to create an hierarchical post without title support #36939 in specs/editor/plugins/custom-post-types.test.js

[ntsekouras]

Cherry-picked this PR to the wp/6.2 branch.

[felixarntz]

Thank you @ntsekouras, apologies I missed this yesterday!