resolve proper aarch64 image names

when automatically downloading fcos for the Apple M1, we needed
to replace a statically defined URL with the dynamically
determined one.

also, it appears boolean qemu options `server` and `onwait` are
not defined as `server=on` and `wait=off`.

[NO TESTS NEEDED]

Signed-off-by: baude <bbaude@redhat.com>
This commit is contained in:
Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f