Previously, we were discarding and re-adding all channel preference switches when a group was toggled. This caused the group switch itself to flicker and sometimes lose the a11y focus as well. Because the group toggle is always at the top, it's not necessary to ever re-sort it (which is the main reason for doing the remove+add dance).
This CL also resurrects ChannelListPreferenceControllerTest which was disabled.
Fixes: 248056830
Test: atest ChannelListPreferenceControllerTest
Change-Id: I5672c102d4571430e26ad6bee92d8c88794214ae
8c40305ad6