slapos_crm: Drop rss image (unused)

master/bt5/slapos_crm/SkinTemplateItem/portal_skins/slapos_crm/rss_feed_image.xml

-<?xml version="1.0"?>
-<ZopeData>
-  <record id="1" aka="AAAAAAAAAAE=">
-    <pickle>
-      <global name="Image" module="OFS.Image"/>
-    </pickle>
-    <pickle>
-      <dictionary>
-        <item>
-            <key> <string>__name__</string> </key>
-            <value> <string>rss_feed_image</string> </value>
-        </item>
-        <item>
-            <key> <string>content_type</string> </key>
-            <value> <string>image/png</string> </value>
-        </item>
-        <item>
-            <key> <string>height</string> </key>
-            <value> <int>32</int> </value>
-        </item>
-        <item>
-            <key> <string>precondition</string> </key>
-            <value> <string></string> </value>
-        </item>
-        <item>
-            <key> <string>title</string> </key>
-            <value> <string>RSS Feed Image</string> </value>
-        </item>
-        <item>
-            <key> <string>width</string> </key>
-            <value> <int>32</int> </value>
-        </item>
-      </dictionary>
-    </pickle>
-  </record>
-</ZopeData>