host-deploy: flush both stdout, stderr at ssh execute

although until unclear why it is needed.

1. flush before java attempt to close using try-with-resources.

2. flush also stderr.

3. perform at one location.

Related-To: https://bugzilla.redhat.com/show_bug.cgi?id=1084911
Change-Id: I14424723f2ef6abff6f3abdc1072e5ac621d4e67
Signed-off-by: Alon Bar-Lev <alonbl@redhat.com>