Shutdown integration scenario faster (#7256)

Signed-off-by: Friedrich Gonzalez <1517449+friedrichg@users.noreply.github.com>

Author: friedrichg

integration/e2e/scenario.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"os"
 	"strings"
+	"sync"
 
 	"github.com/pkg/errors"
 )
@@ -147,12 +148,19 @@ func (s *Scenario) clean() {
 }
 
 func (s *Scenario) shutdown() {
-	// Kill the services in the opposite order.
+	// Kill the services in parallel. We still iterate in reverse order
+	// to respect service dependencies, but we kill them concurrently.
+	var wg sync.WaitGroup
 	for i := len(s.services) - 1; i >= 0; i-- {
-		if err := s.services[i].Kill(); err != nil {
-			logger.Log("Unable to kill service", s.services[i].Name(), ":", err.Error())
-		}
+		wg.Add(1)
+		go func(service Service) {
+			defer wg.Done()
+			if err := service.Kill(); err != nil {
+				logger.Log("Unable to kill service", service.Name(), ":", err.Error())
+			}
+		}(s.services[i])
 	}
+	wg.Wait()
 
 	// Ensure there are no leftover containers.
 	if out, err := RunCommandAndGetOutput(