slapos_rss_style: drop template_software_installation

master/bt5/slapos_rss_style/TestTemplateItem/portal_components/test.erp5.testSlapOSRSSStyleSkins.py

@@ -86,8 +86,7 @@ class TestRSSSyleSkinsMixin(SlapOSTestCaseMixinWithAbort):
   def _makeSoftwareInstallation(self):
     self._makeComputeNode()
     software_installation = self.portal\
-       .software_installation_module.template_software_installation\
-       .Base_createCloneDocument(batch_mode=1)
+       .software_installation_module.newContent(portal_type="Software Installation")
     software_installation.edit(
        url_string=self.generateNewSoftwareReleaseUrl(),
        aggregate=self.compute_node.getRelativeUrl(),