Cache RE object in uri template matcher.

Fix [CVE-2024-23323](GHSA-x278-4w4x-r7ch)

Signed-off-by: Yan Avlasov <yavlasov@google.com>
Signed-off-by: Ryan Northey <ryan@synca.io>

changelogs/current.yaml

@@ -52,6 +52,9 @@ bug_fixes:
   change: |
     Fixed a crash when Envoy is configured for PROXY protocol on both a listener and cluster, and the listener receives
     a PROXY protocol header with address type LOCAL (typically used for health checks).
+- area: url matching
+  change: |
+    Fixed excessive CPU utilization when using regex URL template matcher.
 
 removed_config_or_runtime:
 # *Normally occurs at the end of the* :ref:`deprecation period <deprecated>`