Check debian distribution nested query performance

The following discussion from !53818 (merged) should be addressed:

• @sabrams started a discussion: (+1 comment)

  Having the two level has_many of distribution -> packages -> package_files raises a small concern around query performance as both the feature scales (table gets larger) and depending on the size of any given distribution since we will always have nested loops in the query plan. Even with index usage within each loop, there is potential for this to slow down over time.

  I don't think we need to address it here for the MVC, but it would be a good idea to open a followup issue for revisiting this (and the parallel group-level queries) in the future once the initial feature has been released.