Fix trailing spaces in navigation block classnames

[talldan]

What?

Fixes the very minor issue in #67999, adds some trimming to navigation block classnames

Testing Instructions

1. View a navigation block on the frontend of a site, ensure it's one that's configured to show the Overlay Menu on mobile or always.
2. Open dev tools and either reduce the width of the browser or use the mobile device simulation thing
3. Inspect the navigation hamburger menu (or two buns with no burger) button
4. Check that the wp-block-navigation__responsive-container-open class on the button has no trailing space
5. Click the hamburger button
6. Check that the wp-block-navigation__responsive-container doesn't have two spaces after it.

Screenshots or screencast

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[github-actions]

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Co-authored-by: talldan <talldanwp@git.wordpress.org>
Co-authored-by: ramonjd <ramonopoly@git.wordpress.org>

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[github-actions]

Flaky tests detected in e635f63.
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/12424146647
📝 Reported issues:

• [Flaky Test] Navigates the items list via UP/DOWN arrow keys #64334 in /test/e2e/specs/site-editor/dataviews-list-layout-keyboard.spec.js

[ramonjd]

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