run_remote.go: move registerGceHostIP() call to testImage()

I.e. don't assume that `testHost` is called on a GCE host. Prep for
future patch.

test/e2e_node/runner/remote/run_remote.go

@@ -453,14 +453,6 @@ func registerGceHostIP(host string) error {
 
 // Run tests in archive against host
 func testHost(host string, deleteFiles bool, imageDesc, junitFileName, ginkgoFlagsStr string) *TestResult {
-	if err := registerGceHostIP(host); err != nil {
-		return &TestResult{
-			err:    err,
-			host:   host,
-			exitOk: false,
-		}
-	}
-
 	path, err := arc.getArchive()
 	if err != nil {
 		// Don't log fatal because we need to do any needed cleanup contained in "defer" statements
@@ -555,6 +547,14 @@ func testImage(imageConfig *internalGCEImage, junitFileName string) *TestResult
 	// If we are going to delete the instance, don't bother with cleaning up the files
 	deleteFiles := !*deleteInstances && *cleanup
 
+	if err = registerGceHostIP(host); err != nil {
+		return &TestResult{
+			err:    err,
+			host:   host,
+			exitOk: false,
+		}
+	}
+
 	result := testHost(host, deleteFiles, imageConfig.imageDesc, junitFileName, ginkgoFlagsStr)
 	// This is a temporary solution to collect serial node serial log. Only port 1 contains useful information.
 	// TODO(random-liu): Extract out and unify log collection logic with cluste e2e.