Disable browsed cover art by default

It has become difficult to provide browsed cover artwork given the race
condition between change path commands causing an OBEX level connection
refresh and a connection being required when we browse to receive image
handles at all. As a result, we typically miss the first 15-20 items'
image handles while we're waiting for the BIP connection to complete.

We were able to solve this for current track metadata by asking for it
again upon connecting, but it will require lots of work to be able to do
something similar with browsed content.

For the time being, for the sake of stability and a good UX, we will
disable browsed cover art.

Tag: #compatibility
Bug: 158036761
Test: atest BluetoothInstrumentationTests
Merged-In: I3ba17cf70728501bb7befe9db9439943f546872a
Change-Id: I3ba17cf70728501bb7befe9db9439943f546872a