Middleware route matchers exposed in browser runtime

### Verify canary release - [X] I verified that the issue exists in the latest Next.js canary release ### Provide environment information ```bash Operating System: Platform: darwin Arch: arm64 Version: Darwin Kernel Version 22.4.0: Mon Mar 6 20:59:28 PST 2023; root:xnu-8796.101.5~3/RELEASE_ARM64_T6000 Binaries: Node: 16.15.0 npm: 8.5.5 Yarn: 1.22.18 pnpm: 7.22.0 Relevant packages: next: 13.2.5-canary.30 eslint-config-next: N/A react: 18.2.0 react-dom: 18.2.0 ``` ### Which area(s) of Next.js are affected? (leave empty if unsure) Middleware / Edge (API routes, runtime) ### Link to the code that reproduces this issue https://github.com/vercel/next.js/tree/canary/examples/middleware ### To Reproduce 1. Build the app with `next build` 2. Serve it with `next serve`. 3. Go to browser and load the website 4. Type `console.log(window. __MIDDLEWARE_MATCHERS)` You will get an array of matches which show on which paths middleware runs. In development it is exposed as `__DEV_MIDDLEWARE_MATCHERS` which is even fine. ### Describe the Bug I think matchers config is server side code that you do not want exposed to the client. Not sure for what it is used, so my concern is - why is it even there? Since `matcher` can contain custom regex, that could contain sensitive paths/keywords.. I think that kind of code that should not be that easily accessible (or not accessible at all) could leak or be used for unwanted behaviour. I would be curious to understand why is this needed 👀 ### Expected Behavior `window.__MIDDLEWARE_MATCHERS` is not defined. At very least this should be documented. ### Which browser are you using? (if relevant) _No response_ ### How are you deploying your application? (if relevant) _No response_