PMM server QAN page always says `Loading..` even if we do not have any mysql clients.
If we have not configured any clients QAN page will say There are no mysql instances, but it disappear after few seconds.
- Render a page that displays There are no configured instances for Query Analytics if none are found. Do not disappear this message.
- Include links to relevant Documentation pages:
- Deploying pmm-client: https://www.percona.com/doc/percona-monitoring-and-management/deploy/client/index.html#install-client
- mongodb:queries - soon to come - DOC-521