fix(docs): redirect monitoring-and-debugging to observability (#50576)

This PR will also fix the markdown redirects. 

There's no need to list markdown redirects, `.md` is automatically added
when building the redirects in `www` `next.config.mjs`.

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **Bug Fixes**
- Updated observability documentation redirects to use extension-free
URLs.
- Removed the outdated redirect from the observability access-data page.
- Updated the monitoring and debugging redirect to point to the
extension-free observability guide.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

apps/www/lib/redirects.js

@@ -190,11 +190,6 @@ module.exports = [
     source: '/docs/guides/observability/access-data',
     destination: '/docs/guides/observability',
   },
-  {
-    permanent: true,
-    source: '/docs/guides/observability/access-data.md',
-    destination: '/docs/guides/observability.md',
-  },
   {
     permanent: true,
     source: '/docs/guides/reports/:match*',
@@ -207,8 +202,8 @@ module.exports = [
   },
   {
     permanent: true,
-    source: '/docs/guides/monitoring-and-debugging.md',
-    destination: '/docs/guides/observability.md',
+    source: '/docs/guides/monitoring-and-debugging',
+    destination: '/docs/guides/observability',
   },
   {
     permanent: true,