Remove the tint from taskbar themed icons for dark mode.

We remove the added tint to taskbar themed icons to match how they look
in the hotseat on launcher home screen specifically for dark mode.

Fix: 323952706
Test: Turn on themed icons and dark mode. Compare app icons in taskbar
and in hotseat
Flag: N/A

Change-Id: I4dfe352ca17ef5537e48fcc3cff66ba4fd4f603a