install/rpm: wipe all zypper repos before adding repos-under-test
install/rpm: wipe all zypper repos before adding repos-under-test

Our tests should be designed to not rely on any pre-existing repos. If there are
any pre-existing repos, these can potentially skew test results by causing
unexpected packages/package versions to be installed.

Therefore, wipe any pre-existing repos before adding the repos-under-test.

Signed-off-by: Nathan Cutler <f9d8c66a4e898e67db786769b5b347b640e1a9a6@suse.com>

SUSE/teuthology,dmick/teuthology,ceph/teuthology,SUSE/teuthology,dmick/teuthology,ktdreyer/teuthology,ceph/teuthology,SUSE/teuthology,ktdreyer/teuthology,dmick/teuthology