Fixing flaky bokchoy TeamPageTests

The flaky test problems we've been seeing here are coming from not
waiting long enough after performing actions. By forcing
is_browser_on_page checks to wait until the page is fully loaded
instead of just looking for the presence of a single element, we
ensure that there will not be issues interacting with non-loaded
elements.

TNL-3069

common/test/acceptance/pages/lms/discussion.py

@@ -402,6 +402,7 @@ class InlineDiscussionPage(PageObject):
         return self.q(css=self._discussion_selector + " " + selector)
 
     def is_browser_on_page(self):
+        self.wait_for_ajax()
         return self.q(css=self._discussion_selector).present
 
     def is_discussion_expanded(self):

common/test/acceptance/pages/lms/teams.py

@@ -261,6 +261,7 @@ class TeamPage(CoursePage, PaginatedUIMixin):
 
     def is_browser_on_page(self):
         """Check if we're on the teams list page for a particular team."""
+        self.wait_for_ajax()
         if self.team:
             if not self.url.endswith(self.url_path):
                 return False

common/test/acceptance/tests/lms/test_teams.py

@@ -748,7 +748,6 @@ class CreateTeamTest(TeamsTabBase):
         self.verify_my_team_count(0)
 
 
-@flaky  # TODO fix this, see TNL-3069
 @attr('shard_5')
 @ddt.ddt
 class TeamPageTest(TeamsTabBase):