Fix: Double-free error on RemoteFillService

Symptom:
RemoteFillService was crashed due to IllegalArgumentException
"Service not registered:" at onServiceConnected.

Root cause:
RemoteFillService#onServiceConnected tries to unbind the connection
if mDestroyed is flagged or mBinding is not flagged. It always fails
with IllegalArgumentException.
Both mDestroyed and !mBinding mean the connection was unbound.
You can't unbind the unbound connection. It's not allowed.

Fixes: 73864601
Fixes: 69905688

Change-Id: If5481468ddac7be41accad63e9d5382bc6c029fd