Update test expectation

The health check status may be updated for other reasons on the CI,
which may cause the message to be inaccurate by the time the result is
accessed from the hash

test/new_relic/agent/health_check_test.rb

@@ -329,8 +329,7 @@ def test_update_status_is_a_no_op_when_health_checks_disabled
 
   def test_update_message_works_with_http_arrays
     health_check = NewRelic::Agent::HealthCheck.new
-    health_check.update_status(NewRelic::Agent::HealthCheck::HTTP_ERROR, ['401', :preconnect])
-    result = health_check.instance_variable_get(:@status)[:message]
+    result = health_check.update_status(NewRelic::Agent::HealthCheck::HTTP_ERROR, ['401', :preconnect])
 
     assert_equal 'HTTP error response code [401] recevied from New Relic while sending data type [preconnect]', result
   end