Allow server to start if one of local nodes in docker/kubernetes setup is resolved (#7452)

Allow server to start if one of the local nodes in docker/kubernetes setup is successfully resolved

- The rule is that we need atleast one local node to work. We dont need to resolve the
  rest at that point.

- In a non-orchestrational setup, we fail if we do not have atleast one local node up
  and running.

- In an orchestrational setup (docker-swarm and kubernetes), We retry with a sleep of 5
  seconds until any one local node shows up.

Fixes #6995

cmd/server-main.go

@@ -200,6 +200,8 @@ func serverMain(ctx *cli.Context) {
 		cli.ShowCommandHelpAndExit(ctx, "server", 1)
 	}
 
+	signal.Notify(globalOSSignalCh, os.Interrupt, syscall.SIGTERM)
+
 	// Disable logging until server initialization is complete, any
 	// error during initialization will be shown as a fatal message
 	logger.Disable = true
@@ -305,8 +307,6 @@ func serverMain(ctx *cli.Context) {
 		globalHTTPServerErrorCh <- globalHTTPServer.Start()
 	}()
 
-	signal.Notify(globalOSSignalCh, os.Interrupt, syscall.SIGTERM)
-
 	newObject, err := newObjectLayer(globalEndpoints)
 	if err != nil {
 		// Stop watching for any certificate changes.