container/Containerfile: purge .repo files with secrets before commit

container/Containerfile: purge .repo files with secrets before commit

ceph.repo had creds in it for download.ceph.com/prerelease.
Remove the .repo files we construct, since they're not necessary
once the container is built (no one should be dnf'ing anything
in the container).

Signed-off-by: Dan Mick <dan.mick@redhat.com>
(cherry picked from commit 08432ef54212aa2aba724102854082e76f0cd847)