Hide pair other ear button after device connected via CSIP

The pair other ear button should disappear after both ears of binaural
hearing aids are connected.

Remove checking if CSIP is enabled since CSIP is always enabled in
pairing stage.

Bug: 296646732
Test: check the UI manually
Change-Id: I804819eef41b5d3754ad0a79d9fc1afc66cef5cc