* CustomScrollbar: migrated styles from sass to emotion

* fixes frontend test

* updated changes

* fixed page props and applied changes to all occurences

* moved the getStyles function to the bottom of the file

* made some changes

* fixed snapshot test

* Revert "Merge branch 'refactor-customscrollbar-30354' of https://github.com/grafana/grafana into refactor-customscrollbar-30354"

This reverts commit c45ee30b6b297991a1628e9b21c4121dc78e376c, reversing
changes made to d2645534e39c4ffda30a948f4a892c1c68ec38ca.

* improved props name

* made use of theme variables for style consistency

* fixed snapshot test and updated some theme changes

* removed hover effects from customScrollbar style

* made some changes

* updated some changes

* added label to class names

* changed to a functional component and improved styling

* fixes snapshot test

* fixes small nit

* minor tweaks

Co-authored-by: Torkel Ödegaard <torkel@grafana.com>