Refactor duplicate code in task_validation_test.go

Prior to this commit, many test functions in this file need to get
context based on whether alpha api flag is enabled and this duplicate code
chuck appears multiple times.

Adding a new helper function will make this code chuck reusable when testing
future features that will be developed under alpha feature.

pkg/apis/pipeline/v1beta1/task_validation_test.go

@@ -1041,13 +1041,7 @@ func TestStepAndSidecarWorkspaces(t *testing.T) {
 				Sidecars:   tt.fields.Sidecars,
 				Workspaces: tt.fields.Workspaces,
 			}
-			featureFlags, _ := config.NewFeatureFlagsFromMap(map[string]string{
-				"enable-api-fields": "alpha",
-			})
-			cfg := &config.Config{
-				FeatureFlags: featureFlags,
-			}
-			ctx := config.ToContext(context.Background(), cfg)
+			ctx := getContextBasedOnFeatureFlag("alpha")
 			ts.SetDefaults(ctx)
 			if err := ts.Validate(ctx); err != nil {
 				t.Errorf("TaskSpec.Validate() = %v", err)
@@ -1104,14 +1098,7 @@ func TestStepAndSidecarWorkspacesErrors(t *testing.T) {
 				Sidecars: tt.fields.Sidecars,
 			}
 
-			featureFlags, _ := config.NewFeatureFlagsFromMap(map[string]string{
-				"enable-api-fields": "alpha",
-			})
-			cfg := &config.Config{
-				FeatureFlags: featureFlags,
-			}
-
-			ctx := config.ToContext(context.Background(), cfg)
+			ctx := getContextBasedOnFeatureFlag("alpha")
 			ts.SetDefaults(ctx)
 			err := ts.Validate(ctx)
 			if err == nil {
@@ -1231,14 +1218,7 @@ func TestIncompatibleAPIVersions(t *testing.T) {
 			testName := fmt.Sprintf("(using %s) %s", version, tt.name)
 			t.Run(testName, func(t *testing.T) {
 				ts := tt.spec
-				featureFlags, _ := config.NewFeatureFlagsFromMap(map[string]string{
-					"enable-api-fields": version,
-				})
-				cfg := &config.Config{
-					FeatureFlags: featureFlags,
-				}
-
-				ctx := config.ToContext(context.Background(), cfg)
+				ctx := getContextBasedOnFeatureFlag(version)
 
 				ts.SetDefaults(ctx)
 				err := ts.Validate(ctx)
@@ -1254,3 +1234,14 @@ func TestIncompatibleAPIVersions(t *testing.T) {
 		}
 	}
 }
+
+func getContextBasedOnFeatureFlag(featureFlag string) context.Context {
+	featureFlags, _ := config.NewFeatureFlagsFromMap(map[string]string{
+		"enable-api-fields": featureFlag,
+	})
+	cfg := &config.Config{
+		FeatureFlags: featureFlags,
+	}
+
+	return config.ToContext(context.Background(), cfg)
+}