OCPBUGS-36378: capi: start controllers after WaitGroup is created

Some providers like Azure require 2 controllers to run. If a controller
fails to be spawned (e.g cluster-api-provider-azureaso), we were not
stopping controllers that were already running (e.g. the cluster-api,
cluster-api-provider-azure), resulting in leak processes even though the
Installer reported it had stopped the capi system:

```
ERROR failed to fetch Cluster: failed to generate asset "Cluster": failed to create cluster: failed to run cluster api system: failed to run controller "azureaso infrastructure provider": failed to start controller "azureaso infrastructure provider": timeout waiting for process cluster-api-provider-azureaso to start successfully (it may have failed to start, or stopped unexpectedly before becoming ready)
INFO Shutting down local Cluster API control plane...
INFO Local Cluster API system has completed operations
```

By just changing the order of operations to run the controller *after*
the WaitGroup is created, we are able to properly shutdown all running
controllers and the local control plane in case of error:

```
ERROR failed to fetch Cluster: failed to generate asset "Cluster": failed to create cluster: failed to run cluster api system: failed to run controller "aws infrastructure provider": failed to extract provider "aws infrastructure provider": fake error
INFO Shutting down local Cluster API control plane...
INFO Stopped controller: Cluster API
INFO Local Cluster API system has completed operations
```

Author: r4f4

pkg/clusterapi/system.go

@@ -316,13 +316,6 @@ func (c *system) Run(ctx context.Context) error {
 	// We only show controller logs if the log level is DEBUG or above
 	c.logWriter = logrus.StandardLogger().WriterLevel(logrus.DebugLevel)
 
-	// Run the controllers.
-	for _, ct := range controllers {
-		if err := c.runController(ctx, ct); err != nil {
-			return fmt.Errorf("failed to run controller %q: %w", ct.Name, err)
-		}
-	}
-
 	// We create a wait group to wait for the controllers to stop,
 	// this waitgroup is a global, and is used by the Teardown function
 	// which is expected to be called when the program exits.
@@ -347,6 +340,13 @@ func (c *system) Run(ctx context.Context) error {
 		}
 	}()
 
+	// Run the controllers.
+	for _, ct := range controllers {
+		if err := c.runController(ctx, ct); err != nil {
+			return fmt.Errorf("failed to run controller %q: %w", ct.Name, err)
+		}
+	}
+
 	return nil
 }