Update Secure usage ping to be able to determine number of jobs by user

Parent Issue : https://gitlab.com/gitlab-org/telemetry/issues/308

Problem to solve

Today Secure usage ping data reports the raw number of jobs that are run with Secure scanners. This is good so we can see usage but lacks the ability to see how many individual users are running these. For example, if we have 100 jobs run, it is unclear if we have 10 users running 10 jobs each or 1 user running all 100. This lack of distinction means we cannot report SMAU accurately

Proposal

Update Secure usage ping to be able to determine how many unique users were running the reported jobs. Our goal is to be able to determine at a minimum how many users ran all the various Secure jobs. Additional, nice-to-have metrics would be mean/median/min/max # of jobs per user.

We also need to be able to see the number of users broken down by if they have run any of the scanners. As an example, if the user has run 5 unique scans, we should only count them one time as a Secure user.