tier-0: Enable tmp.mount by default

The long-carried-forward patch to disable `tmp.mount` for RHEL
rears its head again.

tier-0/manifest.yaml

@@ -54,6 +54,7 @@ include:
   - bootc-config.yaml
   - initramfs.yaml
   - autoupdates.yaml
+  - basic-fixes.yaml
 
 packages:
   # Even in tier-0, we have this.  If you don't want SELinux today, you'll need