init_kill_services_test: special case apexd

apexd restarts the device, so it causes flakes here,
especially in presubmit.

Bug: 280514080
Test: init_kill_services_test

Change-Id: I4455704795961f3ae94e29bdf098eca739130973
diff --git a/init/test_kill_services/init_kill_services_test.cpp b/init/test_kill_services/init_kill_services_test.cpp
index 227380d..d9fcd9d 100644
--- a/init/test_kill_services/init_kill_services_test.cpp
+++ b/init/test_kill_services/init_kill_services_test.cpp
@@ -23,8 +23,15 @@
 
 using ::android::base::GetProperty;
 using ::android::base::SetProperty;
+using ::android::base::WaitForProperty;
+using std::literals::chrono_literals::operator""s;
 
 void ExpectKillingServiceRecovers(const std::string& service_name) {
+    // b/280514080 - servicemanager will restart apexd, and apexd will restart the
+    // system when crashed. This is fine as the device recovers, but it causes
+    // flakes in this test.
+    ASSERT_TRUE(WaitForProperty("init.svc.apexd", "stopped", 60s)) << "apexd won't stop";
+
     LOG(INFO) << "hello " << service_name << "!";
     const std::string status_prop = "init.svc." + service_name;
     const std::string pid_prop = "init.svc_debug_pid." + service_name;