test: Remove duplicate kubernetes versions in tests

Replace manual deduplication logic in aaa_download_only_test.go with
util.RemoveDuplicateStrings() function for better consistency and
maintainability.

Previously, when DefaultKubernetesVersion and NewestKubernetesVersion
had the same value (currently both v1.34.0), tests would run twice
for the same version. The manual check and slice manipulation has been
replaced with the existing utility function that handles deduplication
more robustly.

Fixes #21483

Signed-off-by: DeepDN <nemadedeepak1111@gmail.com>

test/integration/aaa_download_only_test.go

@@ -39,6 +39,7 @@ import (
 	"k8s.io/minikube/pkg/minikube/constants"
 	"k8s.io/minikube/pkg/minikube/download"
 	"k8s.io/minikube/pkg/minikube/localpath"
+	"k8s.io/minikube/pkg/util"
 )
 
 // TestDownloadOnly makes sure the --download-only parameter in minikube start caches the appropriate images and tarballs.
@@ -58,16 +59,11 @@ func TestDownloadOnly(t *testing.T) { // nolint:gocyclo
 
 	containerRuntime := ContainerRuntime()
 
-	versions := []string{
+	versions := util.RemoveDuplicateStrings([]string{
 		constants.OldestKubernetesVersion,
 		constants.DefaultKubernetesVersion,
 		constants.NewestKubernetesVersion,
-	}
-
-	// Small optimization, don't run the exact same set of tests twice
-	if constants.DefaultKubernetesVersion == constants.NewestKubernetesVersion {
-		versions = versions[:len(versions)-1]
-	}
+	})
 
 	for _, v := range versions {
 		t.Run(v, func(t *testing.T) {