ErrorProne: BluetoothMapObexServer

Remove a lot of unused variable
Add empty catch log
```
1228: Date has a bad API that leads to bugs; prefer java.time.Instant or LocalDate.
            outAppParams.setMseTime(Calendar.getInstance().getTime().getTime());
                                                                            ^
1812: HeaderSet is final and does not override Object.toString,
so converting it to a string will print its identity instead of useful information.
            Log.v(TAG, "onDelete() " + request.toString());
                                       ^
```

Bug: 236759221
Test: m RUN_ERROR_PRONE=true Bluetooth
Change-Id: I3a399ffdc5717c4622967ffbc8e9fc00d4862fd7