bt: Use group id to select color for icon

This reduces icon color flickering when disconnecting one of the devices
from a device group. Normally we use device address to pick a color but
in case we have a group id we should use it instead, so that the color
does not change when one of the devices disconnects.

Bug: 269067986
Test: manual
Tag: #feature

Change-Id: If72187d050e8ea531b8f2c39e22f3faf1ec14f7b
Merged-In: If72187d050e8ea531b8f2c39e22f3faf1ec14f7b