fix: Prevent deadlock in runComponent when Prepare fails (#45626)

issue: #45608
pr: #45609
When component.Prepare() fails (e.g., net listener creation error), the
sign channel was never closed, causing runComponent to block
indefinitely at <-sign. This resulted in the entire process hanging
after logging the error message.

Changes:
- Move close(sign) to defer statement in runComponent goroutine
- Ensures sign channel is always closed regardless of success/failure
- Allows proper error propagation through future.Await() mechanism

---------

Signed-off-by: Wei Liu <wei.liu@zilliz.com>

cmd/roles/roles.go

@@ -115,6 +115,9 @@ func runComponent[T component](ctx context.Context,
 ) *conc.Future[component] {
 	sign := make(chan struct{})
 	future := conc.Go(func() (component, error) {
+		// Wrap the creation and preparation phase to enable concurrent component startup
+		prepareFunc := func() (component, error) {
+			defer close(sign)
 			factory := dependency.NewFactory(localMsg)
 			var err error
 			role, err := creator(ctx, factory)
@@ -124,9 +127,17 @@ func runComponent[T component](ctx context.Context,
 			if err := role.Prepare(); err != nil {
 				return nil, errors.Wrap(err, "prepare component failed")
 			}
-		close(sign)
 			healthz.Register(role)
 			metricRegister(Registry.GoRegistry)
+			return role, nil
+		}
+
+		role, err := prepareFunc()
+		if err != nil {
+			return nil, err
+		}
+
+		// Run() executes after sign is closed, allowing components to start concurrently
 		if err := role.Run(); err != nil {
 			return nil, errors.Wrap(err, "run component failed")
 		}