Revert "Invalidate the rails cache for project meta xml in show_project_meta"

Added as an external patch in c4a04440
This reverts commit 4a9a792c.

src/api/app/controllers/source_controller.rb

@@ -432,13 +432,6 @@ class SourceController < ApplicationController
     else
       # access check
       prj = Project.get_by_name params[:project]
-      # since users may now see different versions of the
-      # project XML depending on their access permissions
-      # to linked projects, and the cache is global, we must
-      # invalidate the cache before reconstructing the xml.
-      if prj.id
-        Rails.cache.delete("xml_project_#{prj.id}")
-      end
       render xml: prj.to_axml
     end
   end