side-tags are not cleaned up (87 leftovers)

[ppisar]

scratch-build.sh creates side-tags, but it does remove them with "fedpk remove-side-tag TAG" after finnishin a scratch build. That's mandated by https://docs.fedoraproject.org/en-US/rawhide-gating/multi-builds/. It causes Koji to exhaust its resources. (Each side-tag undergoes regenerating a repository on any package change.)

$ fedpkg list-side-tags --user 'bpeck/jenkins-continuous-infra.apps.ci.centos.org' |wc -l
87