Update count checker script to check num_sound_downloads and num_pack_downloads

[alastair]

In https://github.com/MTG/freesound/pull/1057 we add new fields to the profile to store counts of sound and pack downloads. We need to update the report_count_statuses command to also check these values: https://github.com/MTG/freesound/blob/master/general/management/commands/report_count_statuses.py

To implement that we could probably reuse the code from the fill_downloads management command, although this code won't tell us how many (and which) counts were out of sync after fixing them.

[alastair]

We can also delete the accounts fill_downloads management command