Remove remaining references to COMBINED_STATUS_BAR_SIGNAL_FLAGS

The previous CL removes all implementationso f the provider model
combined iconography + call strength policy from the signal controllers.
This CL removes the remaining handful of references fo the flag which
could change some of our layouts.

Test: atest SystemUITests
Test: manual
Bug: 238873748
Change-Id: If36675acbea5c2f1f250fd526a0877e2a59fb3f3