8156959: compiler/codecache/jmx/UsageThresholdExceededSeveralTimesTest.java fails with exit 134

Remove invalid assert in SensorInfo::process_pending_requests.

Reviewed-by: dholmes, coleenp

hotspot/src/share/vm/services/lowMemoryDetector.cpp

@@ -281,8 +281,6 @@ void SensorInfo::oops_do(OopClosure* f) {
 }
 
 void SensorInfo::process_pending_requests(TRAPS) {
-  assert(has_pending_requests(), "Must have pending request");
-
   int pending_count = pending_trigger_count();
   if (pending_clear_count() > 0) {
     clear(pending_count, CHECK);