[Grafana] Major upgrade to v11

[EtienneM]

https://github.com/grafana/grafana/releases/tag/v11.0.0

https://grafana.com/docs/grafana/latest/whatsnew/whats-new-in-v11-0/

[EtienneM]

https://github.com/grafana/grafana/releases/tag/v11.1.0

[EtienneM]

https://github.com/grafana/grafana/releases/tag/v11.1.1
https://github.com/grafana/grafana/releases/tag/v11.1.2
https://github.com/grafana/grafana/releases/tag/v11.1.3

[ipfaze]

https://github.com/grafana/grafana/releases/tag/v11.3.1

[Frzk]

I'm waiting for cmnlib to be reviewed and accepted to create a grafana-buildpack.

Once done, I'll be able to drastically simplify this repo with just a scalingo.json file.

[matthieu526-scalingo]

@Frzk this has now been done, do you think this is work you want to restart?