perf: local ratelimit stats use strCat (#39674)

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Signed-off-by: Boteng Yao <boteng@google.com>

Author: botengyao

source/extensions/filters/listener/local_ratelimit/local_ratelimit.cc

@@ -24,8 +24,8 @@ FilterConfig::FilterConfig(
 bool FilterConfig::canCreateConnection() { return rate_limiter_.requestAllowed({}).allowed; }
 
 LocalRateLimitStats FilterConfig::generateStats(const std::string& prefix, Stats::Scope& scope) {
-  const std::string final_prefix = "listener_local_ratelimit." + prefix;
-  return {ALL_LOCAL_RATE_LIMIT_STATS(POOL_COUNTER_PREFIX(scope, final_prefix))};
+  static constexpr absl::string_view kPrefix = "listener_local_ratelimit.";
+  return {ALL_LOCAL_RATE_LIMIT_STATS(POOL_COUNTER_PREFIX(scope, absl::StrCat(kPrefix, prefix)))};
 }
 
 Network::FilterStatus Filter::onAccept(Network::ListenerFilterCallbacks& cb) {