[centos-stream] Exclude altimages from SIGs

This consist of some iso files which are not
used and rsync also fails[1] for these, let's exclude
these.

[1]
rsync: read error: Connection timed out (110)
rsync error: error in socket IO (code 10) at io.c(801) [receiver=3.1.3]

Change-Id: I3accc16ff8a1e71e499a09e7aae6625e3a183a12

playbooks/roles/mirror-update/files/centos-stream-mirror-update

@@ -75,6 +75,7 @@ echo "Running Centos 9-stream SIGs rsync..."
 $K5START ${RSYNC} \
     --delete \
     --delete-excluded \
+    --exclude="altimages" \
     --exclude="iso" \
     --exclude="debug" \
     --exclude="s390x" \