ci: build s2 template app in pre_build of pre_check stage

This will fail pipeline earlier if template project of S2 cannot pass
the build.

The other builds for the template app, which is not CMake or default
optimization level are put into the build_template_app of build stage.

tools/find_build_apps/common.py

@@ -147,7 +147,8 @@ class BuildItem(object):
         return self._expand(self._build_log_path)
 
     def __repr__(self):
-        return "Build app {} for target {}, sdkconfig {} in {}".format(
+        return "({}) Build app {} for target {}, sdkconfig {} in {}".format(
+            self.build_system,
             self.app_dir,
             self.target,
             self.sdkconfig_path or "(default)",