The LXC image prep script copies the contents of /etc/pki/rpm-gpg to
the container image so that these keys can be used inside the container.
Importantly, /etc/pki/rpm-gpg is only a staging area where keys are
kept on the filesystem and is not the actual set of keys imported
into the package manager database.
For the EPEL key to be properly copied into the LXC container image
it must first be staged into the host /etc/pki/rpm-gpg directory
and then installed using the rpm_key module. If the key is installed
directly using rpm_key then it is not available as a file to copy
into the container image.
Depends-On: https://review.opendev.org/735289
Change-Id: Ifdeb447e1ef000dbe83394f6e5b0ed3c7afc84c5
295c3c0a93