patch PR25448: more debuginfod prometheus metrics

[Frank Ch. Eigler]

Hi -

On Fri, Mar 27, 2020 at 03:47:27PM +0100, Mark Wielaard wrote:
> This looks nice. Do we have to document these anywhere, or are
> prometheus metrics "self documenting"? I assume tools just take what
> they can get from the json export and create graphs based on the name
> count/sum patterns?

Yeah, the naming convention of related metrics (_sum, _count) allows
averages to be auto-calculated.  No, we don't document any of these
formally (and note that in the man page).

Thanks for the review.

- FChE