Start Solr in standalone mode

[raderio]

Currently the container stats Solr in cloud mode.
Add possibility to stat Solr in standalone mode.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. If you believe this is a mistake, please reply to this comment to keep it open. If there isn't one already, a PR to fix or at least reproduce the problem in a test case will always help us get back on track to tackle this.

[epugh]

In the upcoming Solr 10, the default mode for starting Solr will be cloud mode. You will need to pass in a special --user-managed parameter to start it in what is often called "standalone" mode. I don't know if that changes anything about this ticket?