Do not specify jre or jdk if default value applies

Do not specify jre or jdk if default value applies

This drop multiple lines which set openjdk8 as jre or jdk,
similarly to ho karaf-version is not specified if karaf4 is to be used.

Only Persistence project uses openjdk7.

Lines setting jdks and maven cannot be dropped,
as they constitute part of job name.
Similarly to scope for CSIT.

Change-Id: Ic575cb144d4e66ec3c18439984bcd517b6fc7879
Signed-off-by: Vratko Polak <vrpolak@cisco.com>