Fix some bluetooth theming issues.

The ic_lockscreen_ime wasn't being appropriately colored due to
the (now deleted) override of the assets defined in SettingsLib
that were hardcoded teal. By deleting these, the vector drawable
that's tinted with the accent color is used.

Also fixes the pairing dialog to use DeviceDefault themes.

Fixes: 29837825

Change-Id: I66cd57c00f1eec00346d7d10a86cd9be79d6cf5c