In addition to the required web.root setting there is the web.status-url
that might cause some confusion for users as the difference is not
immediately clear.
In order to deprecate the web.status-url setting the following cases
need to be considered:
1. The Github reporter allows configuring the status-url as part of the
pipeline configuration, but already uses the better item URL in
`setCommitStatus()` instead. Here we can simply add a deprecation
warning in case the status-url is configured.
2. The Pagure reporter also allows to configure the status-url and so
far used it for setting the commit status. Analogous to the Github
reporter we can replace this with the item URL and also add a
deprecation warning when it is configured.
3. The no-job, enqueue and start messages still use the global
`status_url` default (now unified to always use the setting from the
system attributes and NOT from the local Zuul config). Since the
`status_url` replacement attribute has already been deprecated in
favor of `item_url` there isn't anything to do here.
After we've removed support for the `status_url` format attribute, we
can also remove the global `web.status_url` setting from the config and
the system attributes in Zookeeper.
Change-Id: If4ed1d7942dd2e7c2351a1eba9892f8503990f1f