For 'yum' backend, only cache dirs following repoclosure-$COMPOSE_ID-$variant.$arch
name convention are created, e.g. repoclosure-DP-1.0-20190822.t.0-Bar-Tools.x86_64
But for 'dnf' backend, the dir name looks like
repoclosure-$COMPOSE_ID-$variant.$arch-$suffix and there are other files
created, e.g.
repoclosure-DP-1.0-20190822.t.0-Bar-Tools.x86_64-df9fe164317e314e
repoclosure-DP-1.0-20190822.t.0-Bar-Tools.x86_64-filenames.solvx
repoclosure-DP-1.0-20190822.t.0-Bar-Tools.x86_64.solv
JIRA: COMPOSE-2565
Signed-off-by: Haibo Lin <hlin@redhat.com>