Fix infinite loop in support flow

The support flow was using `yes` and `no` to mean emergency/not
emergency. But not in all places – in one place it was using
`True`/`False` instead.

We were treating anything other than `yes`/`no` as a non-answer, which
means ask the question again. Because of the `True`/`False` thing, there
was no way of the user providing a valid `yes`/`no` answer. Which means
that we just kept asking them the question again and again and they got
stuck in a loop.

tests/app/main/views/test_feedback.py

@@ -340,8 +340,8 @@ def test_in_business_hours(when, is_in_business_hours):
 
 
 @pytest.mark.parametrize('choice, expected_redirect_param', [
-    ('yes', True),
-    ('no', False),
+    ('yes', 'yes'),
+    ('no', 'no'),
 ])
 def test_triage_redirects_to_correct_url(client, choice, expected_redirect_param):
     response = client.post(url_for('main.triage'), data={'severe': choice})