Fix variable declarations in GCP M4 manager test

Add missing uploadedFiles and err variable declarations that were
causing go vet failures in CI.

Author: gabrielm-splunk

test/appframework_gcp/m4/manager_appframework_test.go

@@ -92,6 +92,8 @@ var _ = Describe("m4appfw test", func() {
 
 			//################## SETUP ##################
 			// Upload V1 apps to GCP for Indexer Cluster
+			var uploadedFiles []string
+			var err error
 			appVersion := "V1"
 			appFileList := testenv.GetAppFileList(appListV1)
 			testcaseEnvInst.Log.Info(fmt.Sprintf("Upload %s apps to GCP for Indexer Cluster", appVersion))