Drop (temporarily) Yelp from ELN/RHEL 10

We're removing WebKitGTK[[0] from RHEL 10 and one of the applications
that are using it is Yelp which is the default help viewer in GNOME[1].
We do have some plans[2] on how to rework the whole thing so the
existing help is diplayed in the default browser. But until we agree
on something (and implement it) we shouldn't block the WebKitGTK
removal and rather temporarily remove it. It used to be required by
Anaconda as well, but the dependency was dropped with [3] which is part
of the ELN [4].

[0] - https://issues.redhat.com/browse/DESKTOP-670
[1] - https://issues.redhat.com/browse/DESKTOP-679
[2] - https://gitlab.gnome.org/GNOME/yelp-tools/-/merge_requests/12
[3] - rhinstaller/anaconda#5335
[4] - https://koji.fedoraproject.org/koji/buildinfo?buildID=2325587

configs/sst_desktop-yelp.yaml

@@ -9,5 +9,4 @@ data:
  - yelp
 
  labels:
- - eln
  - c9s