Mark a pair of flaky service tests

runtime/observatory/tests/service/service.status

Index: runtime/observatory/tests/service/service.status
diff --git a/runtime/observatory/tests/service/service.status b/runtime/observatory/tests/service/service.status
index ae4f1096727d756a2ae6f25109643b4d536a041d..182e71d0f5d1c3d963bed591780c2642571f712f 100644
--- a/runtime/observatory/tests/service/service.status
+++ b/runtime/observatory/tests/service/service.status
@@ -7,6 +7,8 @@ gc_test: Pass, RuntimeError # Issue 26490
 get_allocation_samples_test: Pass, RuntimeError # Inconsistent stack trace
 reload_sources_test: Pass, Slow # Reload is slow on the bots
 get_retained_size_rpc_test: Pass, RuntimeError # Issue 28193
+pause_on_start_and_exit_test: Pass, RuntimeError # Issue 28624
+pause_on_start_then_step_test: Pass, RuntimeError # Issue 28624
 
 [ ($compiler == none || $compiler == precompiler) && ($runtime == vm || $runtime == dart_precompiled) ]
 evaluate_activation_test/instance: RuntimeError # http://dartbug.com/20047