Fix missing translator comments

Turns out if the string literal starts on the next line after the
translation function, then the translator comment is lost.  So, either
close up short strings, or add a dummy empty string on the first line to
concatenate with the real string.

Ugh.

common/lib/xmodule/xmodule/course_module.py

@@ -387,10 +387,10 @@ class CourseFields(object):
         # a role created by a course Instructor to enable a person (the "Coach") to manage the custom course for
         # his students.
         display_name=_("Enable CCX"),
-        # Translators: Custom Courses for edX (CCX) is an edX feature for re-using course content. CCX Coach is
-        # a role created by a course Instructor to enable a person (the "Coach") to manage the custom course for
-        # his students.
         help=_(
+            # Translators: Custom Courses for edX (CCX) is an edX feature for re-using course content. CCX Coach is
+            # a role created by a course Instructor to enable a person (the "Coach") to manage the custom course for
+            # his students.
             "Allow course instructors to assign CCX Coach roles, and allow coaches to manage Custom Courses on edX."
             " When false, Custom Courses cannot be created, but existing Custom Courses will be preserved."
         ),

common/lib/xmodule/xmodule/lti_module.py

@@ -207,18 +207,14 @@ class LTIFields(object):
     ask_to_send_username = Boolean(
         display_name=_("Request user's username"),
         # Translators: This is used to request the user's username for a third party service.
-        help=_(
-            "Select True to request the user's username."
-        ),
+        help=_("Select True to request the user's username."),
         default=False,
         scope=Scope.settings
     )
     ask_to_send_email = Boolean(
         display_name=_("Request user's email"),
         # Translators: This is used to request the user's email for a third party service.
-        help=_(
-            "Select True to request the user's email address."
-        ),
+        help=_("Select True to request the user's email address."),
         default=False,
         scope=Scope.settings
     )