Only send call change intent if states have changed

This CL was originally merged into the previous directory. cherry
picking it to the new repo.

Bug: 162769427
Bug: 146588378
Tag: #stability
Test: Verified by manually looking at logs to check how
      often call change intents are sent.
Test: IOP and BCST, atest BluetoothInstrumentationTests
Change-Id: I45370bd16cd0cac8e96f24fc264c45fda5dfba86