Fix MATTER_TRACING_ENABLED checks.

We were checking MATTTER_TRACING_ENABLED without including the config header
that defines it.

Fixes project-chip#29214

Author: bzbarsky-apple

src/tracing/registry.h

@@ -16,6 +16,7 @@
  */
 #pragma once
 
+#include <matter/tracing/build_config.h>
 #include <tracing/backend.h>
 
 namespace chip {