Update Renovate config

Cleanup Renovate config, aligning to other package configs 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