OPP: Fix "0%" progress even after file transfer finished

When the file is small enough to be sent together with header in one
packet, PrivateOutputStream#write() never calls back ClientOperation,
because OBEX Client has no more data to send.
In this case, response code in ClientOperation is not updated from
default value (-1) until the PrivateOutputStream is closed.
It causes progress bar not updated from 0%.

The patch adds PrivateOutputStream#close() call after the first write
operation when file and header are sent in one packet, and ensures
progress bar to be updated properly.

Bug: 31895670
Test: manual

Change-Id: I735a872b756ab1c8892c2f8bbf2dce51ae24fc5a