Fix scheduler benchmark triggering warn_blocking

WarnIfComponentBlockingGuard compares the `now` passed to
scheduler.call() against real millis() in finish(). Using fake time
ahead of real millis() caused uint32_t underflow in the guard, triggering
blocking warnings. Fix by reading real millis() at the start of each
outer iteration so fake time stays close to wall clock.

tests/benchmarks/core/bench_scheduler.cpp

@@ -72,13 +72,13 @@ static void Scheduler_Call_5IntervalsFiring(benchmark::State &state) {
   }
   scheduler.process_to_add();
 
-  // Must be monotonic — millis_64_from_() tracks rollovers.
-  uint32_t now = millis() + 100;
-
   for (auto _ : state) {
+    // Use real millis() each outer iteration so our fake time stays close
+    // to wall clock — WarnIfComponentBlockingGuard compares the `now` we
+    // pass to scheduler.call() against real millis() in finish().
+    uint32_t now = millis();
     for (int i = 0; i < kInnerIterations; i++) {
       scheduler.call(now);
-      // Advance time by 1ms so intervals are due again next call
       now++;
     }
     benchmark::DoNotOptimize(fire_count);