Revert changes introduced for #28713 (#33320)

Revert changes introduced when trying to address 28713, since this won't fix the problem in question.

changes/28713-gitops-checkbox-status-replica-env

@@ -1 +0,0 @@
-* Refactored PATH fleet/config end-point to use the primary DB node for both persisting changes and fetching modified App Config.

server/service/appconfig.go

@@ -751,7 +751,7 @@ func (svc *Service) ModifyAppConfig(ctx context.Context, p []byte, applyOpts fle
 	}
 
 	// retrieve new app config with obfuscated secrets
-	obfuscatedAppConfig, err := svc.ds.AppConfig(ctxdb.RequirePrimary(ctx, true))
+	obfuscatedAppConfig, err := svc.ds.AppConfig(ctx)
 	if err != nil {
 		return nil, err
 	}