Fixed DAG triggering with parameters

There was a bad cherry-pick when merging apache#15057 that has not
been caught because of quarantined test.

Fixes: apache#16810

airflow/www/views.py

@@ -1523,7 +1523,7 @@ def trigger(self, session=None):
         if request_conf:
             try:
                 run_conf = json.loads(request_conf)
-                if not isinstance(conf, dict):
+                if not isinstance(run_conf, dict):
                     flash("Invalid JSON configuration, must be a dict", "error")
                     return self.render_template(
                         'airflow/trigger.html', dag_id=dag_id, origin=origin, conf=request_conf

tests/www/views/test_views_trigger_dag.py

@@ -52,7 +52,6 @@ def test_trigger_dag_button(admin_client):
     assert run.run_type == DagRunType.MANUAL
 
 
-@pytest.mark.quarantined
 def test_trigger_dag_conf(admin_client):
     test_dag_id = "example_bash_operator"
     conf_dict = {'string': 'Hello, World!'}