Grafana 9 (do NOT merge, WIP still)

[fabio-silva]

• Update packages to Grafana 9.1.1;
• Add monkey patch script (one grafana module is breaking our builds) for now;
• Update grafana-polystat-panel;
• Remove @percona/platform-core as dependency;
• Move to yarn for better dependency management.

[solovevayaroslavna]

I don't see problems, but it would be much better if Anton takes a look at it too, because he has worked much more with this part of the application than I have

[denisok]

@fabio-silva looks like this one should be updated? is this one still WIP?

[fabio-silva]

Newest version: https://github.com/percona/grafana-dashboards/pull/1417 Closing this PR.