We call `Project#mark_stuck_remote_mirrors_as_failed!` from the
`Git::BaseHooksService`. So that gets called every time we push tags
or branches.

Before this would only mark started mirrors as failed if they had
been started 24 hours ago. A push would never take 24 hours,
especially not when we run it so often.

Lowering that threshold 1 hour should at least allow us to retry
broken mirrors more often on pushes.

The timeout for the initial push is set somewhat longer to accommodate
for pushing large repos. Both numbers are currently picked arbitrarily.