perf(perflog): record job and RPC metrics only when telemetry is compiled in

jobQueue, jobStart and jobFinish each called into the metrics registry, so every
job paid for three of them. The recordJob* bodies are compiled out without
telemetry, but the calls were not: each still made a virtual
getMetricsRegistry() call, and each built its argument with JobTypes::name(),
which is a std::map lookup plus an assert. The registry is constructed
unconditionally, so the null test never short-circuited any of it.

Guard the five recording blocks, and the registry include with them: the only
other thing naming that type is the metric macros' expansion, which is also
compiled out. The two in-flight UpDownCounter macros stay unguarded -- they take
only app_, which costs nothing, and the macro drops it.

This is the highest-frequency site in the audit: three calls per job against one
per transaction elsewhere.

src/xrpld/perflog/detail/PerfLogImp.cpp

@@ -2,7 +2,12 @@
 
 #include <xrpld/app/main/Application.h>
 #include <xrpld/telemetry/MetricMacros.h>
+
+#ifdef XRPL_ENABLE_TELEMETRY
+// Only the recording calls below and the metric macros' expansion name the
+// registry, and neither survives with telemetry compiled out.
 #include <xrpld/telemetry/MetricsRegistry.h>
+#endif
 
 #include <xrpl/basics/Log.h>
 #include <xrpl/basics/chrono.h>
@@ -339,8 +344,10 @@ PerfLogImp::rpcStart(std::string const& method, std::uint64_t const requestId)
     // above are released: the OTel call path allocates and takes locks
     // inside the SDK, so holding methodsMutex across it would widen a
     // process-wide critical section for no reason. Mirrors rpcEnd().
+#ifdef XRPL_ENABLE_TELEMETRY
     if (auto* mr = app_.getMetricsRegistry())
         mr->recordRpcStarted(method);
+#endif
 
     // A value that must be able to decrease (UpDownCounter), added at its
     // call site with no MetricsRegistry member/init-line/method. Paired with
@@ -398,6 +405,7 @@ PerfLogImp::rpcEnd(std::string const& method, std::uint64_t const requestId, boo
     // Record RPC completion in OTel metrics pipeline. Mirrors the
     // rpcStart() instrumentation so the finished/errored counters and
     // duration histogram advance with every call.
+#ifdef XRPL_ENABLE_TELEMETRY
     if (auto* mr = app_.getMetricsRegistry())
     {
         if (finish)
@@ -409,6 +417,7 @@ PerfLogImp::rpcEnd(std::string const& method, std::uint64_t const requestId, boo
             mr->recordRpcErrored(method, durationUs.count());
         }
     }
+#endif
 
     // Matching -1 for the +1 recorded in rpcStart(). Placed after the early
     // returns above so it runs only when this request's methods-map entry was
@@ -432,10 +441,17 @@ PerfLogImp::jobQueue(JobType const type, std::string const& name)
         ++counter->second.value.queued;
     }
 
+#ifdef XRPL_ENABLE_TELEMETRY
     // Record job enqueue in OTel metrics pipeline, after the lock above is
     // released so the SDK's work stays outside the critical section.
+    //
+    // Guarded because this runs three times per job, counting jobStart and
+    // jobFinish below. recordJobQueued's body is compiled out, but the call is
+    // not: the virtual getMetricsRegistry() and the JobTypes::name() map lookup
+    // that builds its argument both still happen.
     if (auto* mr = app_.getMetricsRegistry())
         mr->recordJobQueued(JobTypes::name(type), name);
+#endif
 }
 
 void
@@ -470,8 +486,10 @@ PerfLogImp::jobStart(
     // released. jobsMutex is process-wide and taken by every worker thread
     // on every job, so the SDK's allocation and internal locking must not
     // run inside it.
+#ifdef XRPL_ENABLE_TELEMETRY
     if (auto* mr = app_.getMetricsRegistry())
         mr->recordJobStarted(JobTypes::name(type), name, dur.count());
+#endif
 }
 
 void
@@ -499,8 +517,10 @@ PerfLogImp::jobFinish(JobType const type, std::string const& name, microseconds
 
     // Record job finish in OTel metrics pipeline, after the locks above
     // are released, for the same reason as jobStart().
+#ifdef XRPL_ENABLE_TELEMETRY
     if (auto* mr = app_.getMetricsRegistry())
         mr->recordJobFinished(JobTypes::name(type), name, dur.count());
+#endif
 }
 
 void