Fix tox-verify triggering for all branches

Int/Pack's main repo only has a master branch. However, changes are triggering tox-verify jobs for all branches.

https://jenkins.opendaylight.org/releng/job/packaging-tox-verify-nitrogen/15/ : SUCCESS
Logs: https://logs.opendaylight.org/releng/jenkins092/packaging-tox-verify-nitrogen/15
https://jenkins.opendaylight.org/releng/job/packaging-tox-verify-oxygen/15/ : SUCCESS
Logs: https://logs.opendaylight.org/releng/jenkins092/packaging-tox-verify-oxygen/15
https://jenkins.opendaylight.org/releng/job/packaging-tox-verify-carbon/15/ : SUCCESS
Logs: https://logs.opendaylight.org/releng/jenkins092/packaging-tox-verify-carbon/15

https://git.opendaylight.org/gerrit/#/c/66038

First thoughts are that this is related to the change to tox-verify job from global-jjb.

https://git.opendaylight.org/gerrit/#/c/64537/2/jjb/packaging/packaging.yaml