ci: disable bundle analysis for forks (#13198)

The bundle analysis action requires comment permissions which are not
available to PRs from forks.

This PR disables bundle analysis until we can implement this in a
separate workflow as shown in [the docs
here](https://github.com/exoego/esbuild-bundle-analyzer?tab=readme-ov-file#github-action-setup-for-public-repositories).

.github/workflows/main.yml

@@ -718,6 +718,8 @@ jobs:
           DO_NOT_TRACK: 1 # Disable Turbopack telemetry
 
       - name: Analyze esbuild bundle size
+        # Temporarily disable this for community PRs until this can be implemented in a separate workflow
+        if: github.event.pull_request.head.repo.fork == false
         uses: exoego/esbuild-bundle-analyzer@v1
         with:
           metafiles: 'packages/payload/meta_index.json,packages/payload/meta_shared.json,packages/ui/meta_client.json,packages/ui/meta_shared.json,packages/next/meta_index.json,packages/richtext-lexical/meta_client.json'