Disable volume control popup after HFP connected

Volume control toast pops up when answering call with HFP connected
which is not the desired behavior. Avoid this by not passing the flag
to show the volume control UI.
Cherry picked from wear OS
Adding the property bluetooth.hfp_volume_control.enabled default to true

Bug: 263323082
Bug: 152807108
Bug: 142797301
Test: manual
Change-Id: Ia4f1260c7ca3e9d0ed12e54f2a582c48f6ecfe6f
(cherry picked from commit f001df5baf014c67832d7086ade2abcea3270394)