Stop propagating to DOM elements the focusOnMount prop from NavigableToolbar components

[mmtr]

Description

This PR removes the focusOnMount from the props transferred to NavigableMenu when rendering a NavigableToolbar component.

Fixes #11769.

How has this been tested?

Locally by checking in the React devtools that the focusOnMount prop is not passed down to the children.

Screenshots

Before

After

Types of changes

Bug fix

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.

[jorgefilipecosta]

LGTM 👍 Thank you for catching and fixing this bug.
I checked on React dev tools that the prop is not passed down.
I do not see the warning in the console; I'm trying to check why it does not appear in my environment.

[mmtr]

@jorgefilipecosta yeah, I don't see the warning when running locally Gutenberg. I think that the build process is suppressing the warning messages.

I can see it when using the package in another project like Calypso (Automattic/wp-calypso#28427 (comment)).