fix: mixins / loki-resources-overview panel layout

[QuentinBisson]

What this PR does / why we need it:

This PR fixes a layout issue brought up here #13471 (comment)

This now renders as such which is a whole lot better :)

The multi-row approach was taken from the mimir resource overview dashboards

cc @cstyan

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
  • Note that Promtail is considered to be feature complete, and future development for logs collection will be in Grafana Alloy. As such, feat PRs are unlikely to be accepted unless a case can be made for the feature actually being a bug fix to existing behavior.
• Changes that require user attention or interaction to upgrade are documented in docs/sources/setup/upgrade/_index.md
• For Helm chart changes bump the Helm chart version in production/helm/loki/Chart.yaml and update production/helm/loki/CHANGELOG.md and production/helm/loki/README.md. Example PR
• If the change is deprecating or removing a configuration option, update the deprecated-config.yaml and deleted-config.yaml files respectively in the tools/deprecated-config-checker directory. Example PR

[cstyan]

@QuentinBisson thanks for your continued work on the mixin 👍

[QuentinBisson]

My pleasure :)