feat(js): Remove Performance metrics page

This is not really needed anymore, folks should just use span metrics.
I also noticed a redirect was missing for the non-guide variant of the page.

Author: mydea

docs/platforms/javascript/common/tracing/span-metrics/performance-metrics.mdx

@@ -995,7 +995,7 @@ const userDocsRedirects = [
     source: '/platforms/kotlin-multiplatform/:path*',
     destination: '/platforms/kotlin/guides/kotlin-multiplatform/:path*',
   },
-   {
+  {
     source: '/platforms/python/tracing/trace-propagation/:path*',
     destination: '/platforms/python/tracing/distributed-tracing/:path*',
   },
@@ -1036,11 +1036,24 @@ const userDocsRedirects = [
     source: '/platforms/javascript/tracing/trace-propagation/:path*',
     destination: '/platforms/javascript/tracing/distributed-tracing/:path*',
   },
+  {
+    source: '/platforms/javascript//tracing/instrumentation/performance-metrics/',
+    destination: '/platforms/javascript/tracing/span-metrics/',
+  },
   {
     source:
       '/platforms/javascript/guides/:guide/tracing/instrumentation/performance-metrics/',
-    destination:
+    destination: '/platforms/javascript/guides/:guide/tracing/span-metrics/',
+  },
+  {
+    source:
+      '/platforms/javascript//tracing/instrumentation/span-metrics/performance-metrics/',
+    destination: '/platforms/javascript/tracing/span-metrics/',
+  },
+  {
+    source:
       '/platforms/javascript/guides/:guide/tracing/span-metrics/performance-metrics/',
+    destination: '/platforms/javascript/guides/:guide/tracing/span-metrics/',
   },
   {
     source: '/platforms/javascript/guides/:guide/tracing/trace-propagation/:path*',