libbluetooth: Add BT_STATUS_UNEXPECTED_STATE metric

Add granularity to BT_STATUS_FAIL error codes by introducing a new
BT_STATUS_UNEXPECTED_STATE metric, to be used when an effort to find a
device by address or other identifier fails.

Bug: 340296381
Test: m -j
Flag: Exempt, metrics-only change

Change-Id: I0b358f08821cb1904f828b1aa04b1855b41ec8df