main.tf: don't ignore changes in name

Ignoring changes in name means that one can never run terraform
deployments beyond the initial creation of the webapp service. Terraform
will always modify a service in-place but try to use the same name which
negates the point of *setting* the name in the
google_cloud_run_service.webapp resource.

The downside of this is that one can't then deploy changes without
deleting and re-creating random_id.webapp_revision_name resource but
that is at least documented in the README.

main.tf

@@ -96,9 +96,6 @@ resource "google_cloud_run_service" "webapp" {
       # resource be updated.
       template[0].spec[0].containers[0].image,
 
-      # Also the name of the revision will change with each CI deployment
-      template[0].metadata[0].name,
-
       # Some common annotations which we don't care about.
       template[0].metadata[0].annotations["client.knative.dev/user-image"],
       template[0].metadata[0].annotations["run.googleapis.com/client-name"],