Bass: Fix removing pending source operation by timeout

Use proper argument in CANCEL_PENDING_SOURCE_OPERATION message.
Add unit tests to check that it was queued properly.

Bug: 370456946
Flag: Exempt, trivial fix covered with unit tests
Test: atest BassClientStateMachineTest BassClientServiceTest
Change-Id: I965976eefbef068e9d20de82a7cea7ddf8c4da34