(MODULES-11617) Replace apt with apt-cache when using with grep

Author: shubhamshinde360

spec/acceptance/apt_backports_spec.rb

@@ -17,7 +17,7 @@
     end
 
     it 'provides backports apt sources' do
-      run_shell('apt policy | grep --quiet backports')
+      run_shell('apt-cache policy | grep --quiet backports')
     end
   end
 end