Fix: Remove Javascript Metrics; move to Span Metrics (#14198)

This PR removes the `/platforms/javascript/metrics` page and redirects
its traffic to `/platforms/javascript/tracing/span-metrics/`. This
includes a wildcard redirect to cover all JavaScript framework-specific
metrics URLs. The goal is to consolidate JavaScript metrics
documentation under the tracing/span-metrics section

---------

Co-authored-by: Cursor Agent <cursoragent@cursor.com>

Author: 2 people

docs/platforms/javascript/common/metrics/index.mdx

@@ -1068,6 +1068,14 @@ const userDocsRedirects = [
     source: '/platforms/javascript/tracing/trace-propagation/:path*',
     destination: '/platforms/javascript/tracing/distributed-tracing/:path*',
   },
+  {
+    source: '/platforms/javascript/metrics/:path*',
+    destination: '/platforms/javascript/tracing/span-metrics/:path*',
+  },
+  {
+    source: '/platforms/javascript/guides/:guide/metrics/:path*',
+    destination: '/platforms/javascript/guides/:guide/tracing/span-metrics/:path*',
+  },
   {
     source: '/platforms/javascript/tracing/instrumentation/performance-metrics/',
     destination: '/platforms/javascript/tracing/span-metrics/',