caddy-frontend/test: Force promise run during test

--force with --check-anomaly makes monitor.runpromise execute the promise
unconditionally, even for testless ones.

software/caddy-frontend/test/test.py

@@ -378,7 +378,9 @@ class TestDataMixin(object):
         plugin_status, plugin_result = subprocess_status_output([
           runpromise_bin,
           '-c', monitor_conf,
-          '--run-only', plugin
+          '--run-only', plugin,
+          '--force',
+          '--check-anomaly'
         ])
         # sanity check
         if 'Checking promise %s' % plugin not in plugin_result: