Make carrier icons update on theme change

Previously, the colors did not update because the background was
a fixed black. Now that background blur is enabled, the icon color
needs to update with the theme/mode.

Bug: 405266952
Flag: com.android.systemui.notification_shade_blur
Test: ran affected tests; manually verified
Change-Id: I246b33f886bc426e61fc5b8c91868f27539dc5f1