ContextMap: Remove connection references when an app is removed

This fixes an issue which could cause a stale Bluetooth address to be
used. The issue would manifest itself when an app is added with a
connection ID, then the app is removed and app is re-added, causing
the original connection ID (which could be stale) to be used.

Bug: 30765855
Change-Id: Idacbbfb07d895bf9276fdd986100e832a54d81b0