Put search step back into project build task (#4655)

It got removed a bit early and if we don't set an outcome, search files
aren't synced correctly.

Refs #4638

readthedocs/projects/tasks.py

@@ -692,6 +692,7 @@ def build_docs(self):
                 version=self.version,
                 max_lock_age=getattr(settings, 'REPO_LOCK_SECONDS', 30)):
             outcomes['html'] = self.build_docs_html()
+            outcomes['search'] = self.build_docs_search()
             outcomes['localmedia'] = self.build_docs_localmedia()
             outcomes['pdf'] = self.build_docs_pdf()
             outcomes['epub'] = self.build_docs_epub()
@@ -723,6 +724,14 @@ def build_docs_html(self):
 
         return success
 
+    def build_docs_search(self):
+        """Build search data."""
+        # TODO rely on config parameter here when Project.documentation_type is
+        # removed in #4638. Mkdocs has no search currently
+        if self.project.documentation_type == 'mkdocs':
+            return False
+        return self.build_search
+
     def build_docs_localmedia(self):
         """Get local media files with separate build."""
         if 'htmlzip' not in self.config.formats: