KeepLongStdio argument for JUnit publisher

JUnit publisher had hardcoded 'true' for bool option
if to keep long output log for results.

This changes it to be configurable via keep-long-stdio option.

Change-Id: I0b3ddef120e08b61a7cd327807c18353ea427a34
Merge "KeepLongStdio argument for JUnit publisher"