Don't mix UI and print job state

In PrintActivity.OnPause we set the print job state based on the
PrintActivity state. The issue was that FINISHED was interpreted as
"cancel print job". Actually with FINISHED does not tell what state the
job should be in.

The only purpose of the finished state was to guard against
double-invocation of doFinish().

Hence remove this recently introduced state and use a simple boolean to
guard against doule invocation of doFinish().

Bug: 27760331
Change-Id: I0767c2b0b9c28e8904647cc832c236f67f92bcfe