fix: Don't crash when unable to post comment to PR (#5669)

... by not ever posting such comments from this workflow.

There will be a separate PR for the other workflow that does post
comments, because it needs to be in the master branch.

Part of #5659.

.github/workflows/check_clang_format.yml

@@ -1,5 +1,7 @@
 name: Check clang format
 
+# N.B.: Runs with a read-only repo token.  Safe(ish) to check out the
+# submitted branch.
 on: [pull_request]
 
 jobs:
@@ -15,14 +17,7 @@ jobs:
         clangFormatVersion: 12
         style: Google
 
-    - uses: actions/github-script@v5
+    # The Report clang format workflow (report_clang_format.yml) will
-      if: failure()
+    # run (if required) after this one to post a comment to the PR.
-      with:
+    # (Note that the version of that workflow run will be the one on
-        script: |
+    # the master (default) branch, not the PR target branch.)
-          console.log(context.issue.number)
-          github.rest.issues.createComment({
-            issue_number: context.issue.number,
-            owner: context.repo.owner,
-            repo: context.repo.repo,
-            body: 'It looks like some of your files have not been formatted properly. Please run `npm run format`.'
-          })