help: Fix structure of markdown context logic.

Refactoring in this file had resulted in the logic for
html_settings_link being duplicated and extra logic being needed to
ensure these variables were set where they were needed.

This fixes subscriptions_html not being rendered properly in the /help
and /api pages, in addition to removing duplicate code.

zerver/tests/test_docs.py

@@ -153,10 +153,10 @@ class IntegrationTest(TestCase):
         self.assertEqual(context["api_url"], "http://mysubdomain.testserver/api")
         self.assertTrue(context["html_settings_links"])
 
-    def test_integration_view_html_settings_links(self) -> None:
-        context = dict()
-        context['html_settings_links'] = False
-        add_integrations_context(context)
+    def test_html_settings_links(self) -> None:
+        context = dict()  # type: Dict[str, Any]
+        with self.settings(ROOT_DOMAIN_LANDING_PAGE=True):
+            add_api_uri_context(context, HostRequestMock())
         self.assertEqual(
             context['settings_html'],
             'Zulip settings page')
@@ -165,8 +165,17 @@ class IntegrationTest(TestCase):
             'streams page')
 
         context = dict()
-        context['html_settings_links'] = True
-        add_integrations_context(context)
+        with self.settings(ROOT_DOMAIN_LANDING_PAGE=True):
+            add_api_uri_context(context, HostRequestMock(host="mysubdomain.testserver"))
+        self.assertEqual(
+            context['settings_html'],
+            '<a href="../../#settings">Zulip settings page</a>')
+        self.assertEqual(
+            context['subscriptions_html'],
+            '<a target="_blank" href="../../#streams">streams page</a>')
+
+        context = dict()
+        add_api_uri_context(context, HostRequestMock())
         self.assertEqual(
             context['settings_html'],
             '<a href="../../#settings">Zulip settings page</a>')