Cleanup Renovate config, aligning to [other package configs](https://repo1.dso.mil/big-bang/apps/sandbox/mimir/-/blob/main/renovate.json?ref_type=heads) as much as possible, including: * Remove `"commitMessagePrefix": "SKIP UPDATE CHECK"` * Ensuring `"renovate", "kind::maintenance", "team::Observability"` labels are present * Update `"enabledManagers"` to use current standards: `["custom.regex", "helm-values", "helmv3"]` * Add appropriate `"postUpgradeTasks"` * Convert `"regexManagers"` to `"customManagers"` as needed (preferably to include all app/image/chart version regex managers) Test changes with the [renovate-runner](https://repo1.dso.mil/big-bang/pipeline-templates/renovate-runner/-/blob/main/dev/TESTING_DEVELOPMENT.md?ref_type=heads)