chore: consolidate cleanup workflows into cleanup-namespace-by-name

[adskyiproger]

• cleanup-namespace-by-name.yml is now the single cleanup: it can be run by hand or called as a reusable workflow
• It skips with a warning, instead of failing, when the namespace has keep_namespace=true
• cleanup-namespaces.yml (hourly) only finds stale namespaces and calls the single cleanup for each one
• Remove cleanup-e2e-environment.yml; opencrvs-core dispatches cleanup-namespace-by-name.yml with opencrvs- instead
• deploy-e2e-environment.yml sets keep_namespace from the run's keep-e2e input, so a removed '🔒 Keep e2e' label no longer protects the namespace from cleanup