Re-enable unit test in A2dpServiceTest for EVENT_TYPE_CODEC_CONFIG_CHANGED

Previously, the unit test for handling of EVENT_TYPE_CODEC_CONFIG_CHANGED
was disabled because of a bug in the BluetoothCodecStatus.equals()
implementation. Now the implementation is fixed, hence the unit test
is re-enabled.

Bug: 73404858
Bug: 73379307
Test: Unit test (in packages/apps/Bluetooth)
  runtest --path tests/unit/src/com/android/bluetooth/a2dp/A2dpServiceTest.java

Change-Id: I46034b955cd56fd8ae9daac5f4d4dd14ad792982