RichText Text Color formatting option still available with empty color palette

[dougwollison]

Describe the bug
In version 7.5, if I "register" an empty color palette and "disable-custom-colors" via add_theme_support, the new Text Color formatting option added by #16014 will still show, with an empty popover.

To reproduce
Steps to reproduce the behavior:

1. Add the following code to your theme's after_theme_setup hook:

add_theme_support( 'editor-color-palette', array() );
add_theme_support( 'disable-custom-colors' );

2. Open the editor and highlight some text, then open the Formats flyout; the Text Color option will still be present.
3. Click on the Text Color option, it will present you with an empty color palette popover with just a clear button.

Expected behavior
The Text Color option should be removed entirely. I can work around this via unregisterFormatType, but it should not be necessary and instead follow the pattern now present in the "Background & Text Color" panel on paragraphs/buttons/etc when no preset or custom colors/gradients are available.

Screenshots

Additional context

• Using the Gutenberg 7.5.0 plugin