Fix devtools experiment UserMetrics and presubmit check

There are missing entries for DevTools experiment in the UserMetrics emun, and the presubmit check has been broken so the issue didnt get caught.
This CL fix the DevTools experiment userMetrics and presubmit check

Bug: 1226082
Change-Id: I881a846b3d988746fb96ffd91eb16789198c2e3a
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/3002943
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Mathias Bynens <mathias@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
diff --git a/scripts/check_experiments.js b/scripts/check_experiments.js
index 1fcd199..82bbb3a 100644
--- a/scripts/check_experiments.js
+++ b/scripts/check_experiments.js
@@ -148,7 +148,7 @@
 }
 
 function main() {
-  const mainImplPath = path.resolve(__dirname, '..', 'front_end', 'main', 'MainImpl.ts');
+  const mainImplPath = path.resolve(__dirname, '..', 'front_end', 'entrypoints', 'main', 'MainImpl.ts');
   const mainImplFile = fs.readFileSync(mainImplPath, 'utf-8');
 
   const userMetricsPath = path.resolve(__dirname, '..', 'front_end', 'core', 'host', 'UserMetrics.ts');