fix: hovered menubutton icon does not disappear

[smhigley]

Previous Behavior

We had a stray :hover style that made icons invisible on hover in expanded menubuttons:

New Behavior

Uses the correct color token (Highlight) for the color, which matches the color/bg color pair used in Button's hover styles

Related Issue(s)

Fixes an issue found while debugging icon high contrast color issues

[fabricteam]

📊 Bundle size report

Package & Exports	Baseline (minified/GZIP)	PR	Change
react-button MenuButton	41.916 kB 12.119 kB	41.919 kB 12.108 kB	3 B -11 B
react-button SplitButton	49.933 kB 13.693 kB	49.936 kB 13.681 kB	3 B -12 B
react-components react-components: entire library	1.1 MB 272.015 kB	1.1 MB 272.006 kB	3 B -9 B

Unchanged fixtures

Package & Exports	Size (minified/GZIP)
react-breadcrumb @fluentui/react-breadcrumb - package	113.699 kB 31.498 kB
react-button Button	37.104 kB 10.766 kB
react-button CompoundButton	43.518 kB 12.068 kB
react-button ToggleButton	53.037 kB 12.528 kB
react-card Card - All	101.248 kB 28.626 kB
react-card Card	94.022 kB 26.806 kB
react-card CardFooter	14.355 kB 5.79 kB
react-card CardHeader	16.888 kB 6.669 kB
react-card CardPreview	14.42 kB 5.922 kB
react-components react-components: Button, FluentProvider & webLightTheme	69.14 kB 20.137 kB
react-components react-components: Accordion, Button, FluentProvider, Image, Menu, Popover	218.317 kB 63.258 kB
react-components react-components: FluentProvider & webLightTheme	44.447 kB 14.59 kB
react-dialog Dialog (including children components)	99.724 kB 29.912 kB
react-message-bar MessageBar (all components)	24.722 kB 9.205 kB
react-portal-compat PortalCompatProvider	8.39 kB 2.64 kB
react-tag-picker @fluentui/react-tag-picker - package	183.584 kB 55.264 kB
react-timepicker-compat TimePicker	107.387 kB 35.758 kB

_{🤖 This report was generated against 12d545e2f9eda489784fc1c4869a70fd50a4f5c7}

[fabricteam]

Perf Analysis (@fluentui/react-components)

No significant results to display.

All results

Scenario	Render type	Master Ticks	PR Ticks	Iterations	Status
Avatar	mount	609	633	5000
Button	mount	312	306	5000
Field	mount	1142	1132	5000
FluentProvider	mount	710	725	5000
FluentProviderWithTheme	mount	85	79	10
FluentProviderWithTheme	virtual-rerender	37	37	10
FluentProviderWithTheme	virtual-rerender-with-unmount	74	72	10
MakeStyles	mount	866	885	50000
Persona	mount	1788	1715	5000
SpinButton	mount	1405	1395	5000
SwatchPicker	mount	1643	1679	5000