Add memunreachable to hwasan-presubmit.

The offending tests have been skipped, can enable the rest.

Bug: 229317612
Change-Id: I8eca4268f8d69b862da19f403be0fc25417ddf6e
diff --git a/TEST_MAPPING b/TEST_MAPPING
index 2db0efe..08fac4f 100644
--- a/TEST_MAPPING
+++ b/TEST_MAPPING
@@ -73,6 +73,9 @@
     },
     {
       "name": "malloc_hooks_system_tests"
+    },
+    {
+      "name": "memunreachable_unit_test"
     }
   ]
 }