CloudFlare Workers seems to only see Build Variables & Secrets on main branch on some projects

### Describe the Bug

CloudFlare Workers - Build Variables & Secrets don't appear consistently in build jobs.

### Expected Behavior

I have an NPM_TOKEN registered in multiple workers so that during the build phase, a private NPM module can be installed. This works in some workers but not others.

### Steps to Reproduce

1. If you visit https://dash.cloudflare.com/aa1e065f6f6da808def1292426bed033/workers/services/view/greg-l-turnquist/production/settings, you can see clearly that NPM_TOKEN is set. And if you dig in, this value has been set for some time.
2. In the Deployments version history, this works just fine WHEN you build on main branch. However, any builds NOT on main branch fail due to NPM_TOKEN not being visible.
3. This implies that setting NPM_TOKEN doesn't end up being universal.

Contrast this with another CloudFlare Worker, that seems to build just fine.

1. If you check out https://dash.cloudflare.com/aa1e065f6f6da808def1292426bed033/workers/services/view/pro-coder-io/production/settings, it also has NPM_TOKEN configured. And it builds fine on main branch.
2. But it ALSO builds fine on branch builds as recently as 15 days ago => https://dash.cloudflare.com/aa1e065f6f6da808def1292426bed033/workers/services/view/pro-coder-io/production/builds/8e058b56-e576-4f3c-9452-46f545c12acf

This is wholly inconsistent behavior, implying something under the hood has changed.

まず、レポートにリンクされている greg-l-turnquist と pro-coder-io の Cloudflare Workers の設定およびデプロイ履歴を比較します。main ブランチと main 以外のブランチでビルドを再現し、各ビルド中に設定された NPM_TOKEN が利用可能かを確認します。ブランチに依存する挙動が再現され、その原因が特定されるか、ビルドの裏付けとなる証拠とともに文書化されれば完了です。

索引モデルが issue の本文から書いたものです。