Certain pages (e.g. the group wide issues page) filter miletones by
their title. Without an index this will result in a sequence scan on a
large dataset increasing the total loading time of a page.

InfluxDB over UDP doesn't use authentication, thus there's no need for
these settings.

This removes the need for Sidekiq and any overhead/problems introduced
by TCP. There are a few things to take into account:

1. When writing data to InfluxDB you may still get an error if the
   server becomes unavailable during the write. Because of this we're
   catching all exceptions and just ignore them (for now).
2. Writing via UDP apparently requires the timestamp to be in
   nanoseconds. Without this data either isn't written properly.
3. Due to the restrictions on UDP buffer sizes we're writing metrics one
   by one, instead of writing all of them at once.