Temporarily remove text decoration from Nav block

[tellthemachines]

Description

Temporary patch for buggy behaviour in Navigation block text-decoration, as described in #37726. We can re-enable text decoration once #36345 or similar is merged.

This follows on from discussion in #37738.

How has this been tested?

Create a Navigation block. In the block sidebar, under "Typography", the "Decoration" option should no longer be available.

Screenshots

Types of changes

Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• I've tested my changes with keyboard and screen readers.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR (please manually search all *.native.js files for terms that need renaming or removal).
• I've updated related schemas if appropriate.

[jasmussen]

Thanks for the PR, it's working well. Before:

After:

As you note, the feature will return, but since the current implementation is buggy in a few unexpected ways, it seems best to not launch with this.

[jasmussen]

@noisysocks Can we backport this one, do you think?