distro/rhel8: explicitly enable google agent services for 8.4

The google-guest-agent services don't get enabled on 8.4.  The reason
for this is currently unknown.  Enabling them explicitly works.

internal/distro/rhel8/distro.go

@@ -723,6 +723,7 @@ func newDistro(distroName string) distro.Distro {
 			"greenboot-task-runner",
 			"redboot-auto-reboot",
 			"redboot-task-runner")
+
 	}
 
 	if !(rd.isRHEL() && versionLessThan(rd.osVersion, "8.6")) {
@@ -1729,6 +1730,19 @@ func newDistro(distroName string) distro.Distro {
 		},
 	}
 
+	if rd.osVersion == "8.4" {
+		// NOTE(akoutsou): these are enabled in the package preset, but for
+		// some reason do not get enabled on 8.4.
+		// the reason is unknown and deeply myserious
+		defaultGceByosImageConfig.EnabledServices = append(defaultGceByosImageConfig.EnabledServices,
+			"google-oslogin-cache.timer",
+			"google-guest-agent.service",
+			"google-shutdown-scripts.service",
+			"google-startup-scripts.service",
+			"google-osconfig-agent.service",
+		)
+	}
+
 	gceImgType := imageType{
 		name:     "gce",
 		filename: "image.tar.gz",