According to someone from Datadog, this was generating tags like "knowledgeable_
people_who_put_this_course_together._this_is_harvard._you_can_t_tell_us_there_s_
a_shortage_of_editorial_talent." They say that they can handle tens or hundreds
of unique tags but not thousands. Given that we have a unique URL for each
thread, we can't even use that as a tag. Thus, all tags are removed for now
until we can determine whether there is a useful set of tags with small enough
cardinality. In light of this, I did not investigate why the long tag mentioned
above was being generated.

According to someone from Datadog, this was generating tags like "knowledgeable_
people_who_put_this_course_together._this_is_harvard._you_can_t_tell_us_there_s_
a_shortage_of_editorial_talent." They say that they can handle tens or hundreds
of unique tags but not thousands. Given that we have a unique URL for each
thread, we can't even use that as a tag. Thus, all tags are removed for now
until we can determine whether there is a useful set of tags with small enough
cardinality. In light of this, I did not investigate why the long tag mentioned
above was being generated.

The LMS comment client previously would try to parse the response
as JSON, choke, and return a 500 to the client. Now, the LMS client
displays a message indicating that the forums are down for
maintenance.

[Hopefully fix #34992235]