registry: remove accidentally added --insecure-registry feature

If `--insecure-registry mydomain.com` was specified, it would match a registry at mydomain.com on any port.
This was accidentally added in #9735 and is now being reverted.

Signed-off-by: Tibor Vass <teabee89@gmail.com>
Merge pull request #9754 from tiborvass/remove-insecure-registry-all-ports

registry: remove accidentally added --insecure-registry feature