fix: use image pull secrets instead of registries.yaml to reference private repositories

While this will now more or less require a local docker login - which can be overridden by setting the image-pull-secrets property - this ensures every deploy has a valid context.

One annoying thing is that the secret is per-app vs global, meaning that if the secret must be rotated, all apps need to be redeployed. A future change can fix that by deploying a global secret, or if folks really desire, this can be done by setting the image-pull-secrets property on the app/globally.

plugins/scheduler-k3s/src/triggers/triggers.go

@@ -35,10 +35,6 @@ func main() {
 	case "post-delete":
 		appName := flag.Arg(0)
 		err = scheduler_k3s.TriggerPostDelete(appName)
-	case "post-registry-login":
-		server := flag.Arg(0)
-		username := flag.Arg(1)
-		err = scheduler_k3s.TriggerPostRegistryLogin(server, username)
 	case "report":
 		appName := flag.Arg(0)
 		err = scheduler_k3s.ReportSingleApp(appName, "", "")