Build: Bug in `target_url`, failure to add "success" status if no external version exists (#10369)
* Clarifications to state vs status
* Use an absolute URL, including the "https://<domain>" for versions
* Update tests with new Version.get_absolute_url implementation
* Revert a change: Always set `self.data.build["success"] = False` in on_failure
* Don't use URLValidator in tests