ART: Simplify atomic.h

Prefer std::atomic operations over wrappers in atomic.h. Exceptions
are cases that relate to the Java data memory operations and CAS
operations.

Bug: 71621075
Test: art/test.py --host -j32
Test: art/test.py --target --64 -j4
Change-Id: I9a157e9dede852c1b2aa67d22e3e604a68a9ef1c
diff --git a/runtime/monitor.h b/runtime/monitor.h
index 384ebbe..6b7604e 100644
--- a/runtime/monitor.h
+++ b/runtime/monitor.h
@@ -130,7 +130,7 @@
   bool IsLocked() REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!monitor_lock_);
 
   bool HasHashCode() const {
-    return hash_code_.LoadRelaxed() != 0;
+    return hash_code_.load(std::memory_order_relaxed) != 0;
   }
 
   MonitorId GetMonitorId() const {