Review and annotate Apache configurations

[garrettr]

The Apache configuration needs to be reviewed, annotated, and potentially revised, because:

• Some if its directives may be redundant/pointless
• There are few comments, which makes the configuration hard to audit.

Follow-up to #1763 (comment).

[garrettr]

I got started on this while I was working on #1777, but we decided to focus on making the minimal changes necessary to resolve #1763 for the 0.4 release and defer a more thorough overhaul of the Apache configs for a later release.

So it's available to anyone who's interested, I pushed a work-in-progress branch of the additional review and annotation that I did while working on #1777.

[eloquence]

Candidate for a time-boxed review given the transition to Focal, but may end up getting bumped off the milestone.

[eloquence]

@conorsch has committed to helping with said time-boxed review, but a stretch goal for 1.8.0.