Add Application Setting to configure Container Registry token expire delay (default 5min)

This adds an option to configure Container Registry token expire delay. The default is set to 5mins (something that is also used by Docker Hub).

What is left:
* [x] Write test to check the expire_delay

Fixes: https://gitlab.com/gitlab-org/gitlab-ce/issues/17890

@stanhu I think that this should land in patch release of 8.8.

See merge request !4364