Geo: Wiki not synced after becoming enabled

From https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/5089#note_64606033:

What about the reverse case: if someone enables the Wiki after it has been disabled, is there a way we can tell to force a Wiki sync? I think @vsizov and I discussed this somewhere, but now I can't remember. :) One way to solve that would be to copy the state of the Wiki enabled flag into the registry and compare. That is outside of this merge request, though. :)

• Confirm that this actually occurs

A couple possible fixes:

• Copy the state of the Wiki enabled flag into the registry and compare
• Ensure a RepositoryUpdatedEvent is created when a wiki is enabled/disabled (this may already be the case) with the necessary data for LogCursor::Daemon to flag resync_wiki