Non-performant code causing purge (invalidate content) api to timeout

[mitchell852]

POST /api/1.2/user/current/jobs creates a purge job which involves inserting a record in the Job table, snapshotting regex_revalidate.config and setting upd_pending flag on each server of the applicable CDN to 1.

This process takes too long and causes a timeout.

I suspect the offending code is in snapshot_regex_revalidate() of https://github.com/Comcast/traffic_control/blob/master/traffic_ops/app/lib/MojoPlugins/Job.pm

specifically, the identical query performed for each server found on line 58 and 59.