Intensify recommendation gradient and scale the cover.

Improve the view of new recommendation card by using a new gradient and
scale the cover to 125%. Also, fix the change in gradient color in media
players and recommendation items by using drawable mutations in order
not to change the original state that is shared among drawables of the
same resource.

Bug: 271163892
Fixes: 268525377
Test: atest MediaControlPanelTest
Test: checked the new view of recommendation card.
Change-Id: Ie3619ea4ebbfcea082eb87d3e461347b7bcc4f8d