Remove nemo-extension-xreader, obsoleted by xreader (#1609294)

Per @robatino, xreader in stable updates for F27 and F28 and in
Rawhide obsoletes nemo-extension-xreader, but because of this
comps entry, `dnf groupinstall cinnamon-desktop` tries to pull
in the nemo-extension-xreader package and an old xreader. Let's
take it out.

Signed-off-by: Adam Williamson <awilliam@redhat.com>

comps-f27.xml.in

@@ -582,7 +582,6 @@
       <packagereq>imsettings-cinnamon</packagereq>
       <packagereq>initial-setup-gui</packagereq>
       <packagereq>metacity</packagereq>
-      <packagereq>nemo-extension-xreader</packagereq>
       <packagereq>nemo-fileroller</packagereq>
       <packagereq>nemo-image-converter</packagereq>
       <packagereq>nemo-preview</packagereq>

comps-f28.xml.in

@@ -582,7 +582,6 @@
       <packagereq type="mandatory">imsettings-cinnamon</packagereq>
       <packagereq type="mandatory">initial-setup-gui</packagereq>
       <packagereq type="mandatory">metacity</packagereq>
-      <packagereq type="mandatory">nemo-extension-xreader</packagereq>
       <packagereq type="mandatory">nemo-fileroller</packagereq>
       <packagereq type="mandatory">nemo-image-converter</packagereq>
       <packagereq type="mandatory">nemo-preview</packagereq>

comps-f29.xml.in

@@ -580,7 +580,6 @@
       <packagereq type="mandatory">imsettings-cinnamon</packagereq>
       <packagereq type="mandatory">initial-setup-gui</packagereq>
       <packagereq type="mandatory">metacity</packagereq>
-      <packagereq type="mandatory">nemo-extension-xreader</packagereq>
       <packagereq type="mandatory">nemo-fileroller</packagereq>
       <packagereq type="mandatory">nemo-image-converter</packagereq>
       <packagereq type="mandatory">nemo-preview</packagereq>