INTTEST-71: Update nexus release url link
post-carbon the release URL changed from /distribution-karaf
to just /karaf. The controller upgrade suite was still pulling
a carbon release to install an "older" ODL because of this.
Since Magnesium CSIT is configured to only use jdk11 and
Carbon will not start with jdk11 the job was broken.
The changes here will also ensure that the suite will find
and use the previous major version as the "old" controller
install.
Change-Id: I1312fdb95a5969fc86fd1c20afd90e637bbc6043
Signed-off-by: Jamo Luhrsen <jluhrsen@gmail.com>