Rename the "delay" parameter to parseRetryAfter to "fallbackDelay"
Rename the "delay" parameter to parseRetryAfter to "fallbackDelay"

... making its purpose clearer.

Signed-off-by: Miloslav Trmač <9c008e38982a5397deb855345fb164f0558459ae@redhat.com>

containers/image,containers/image