ami: update Grafana to 9.0.7 (#4218)

[hugoShaka]

Fixes #4218

The PR:

• Bumps the Grafana version
• Fixes the packer script failing when DEBUG is unset
• Makes Nginx propagate the Host header required since https://grafana.com/blog/2022/02/08/grafana-7.5.15-and-8.3.5-released-with-moderate-severity-security-fixes/
• Makes Nginx proxy websocket calls properly (kinda necessary since grafana 8)
• Retab Nginx conf files that were a mix of tabs and spaces
• Makes Terraform compute s3 files' md5 to detect and apply changes

[hugoShaka]

Note: I'm not sure if this should be backported to v9/v10.

Pros:

• this includes a bunch of Grafana security fixes
• The terraform md5 computation is a painful gotcha
• Our monitor instances are mainly stateless and this has no interaction with the product

Cons:

• this would break the semver, biggets change is the grafana renderer removal

[r0mant]

Should be ok to just keep this update for master branch.