Update queries for better monitoring

See merge request !23

Add ability to query row counts

This commit allows for queries which only request for row counts to be
gathered and written for Prometheus to gather.

At this time 3 simple queries are added which monitor how many projects
are orphaned and/or pending_delete, though the structure of the code
allows for easily adding more queries which do
SELECT COUNT(<whatever>) FROM <whatever>;

See merge request !21

This commit allows for queries which only request for row counts to be
gathered and written for Prometheus to gather.

At this time 3 simple queries are added which monitor how many projects
are orphaned and/or pending_delete, though the structure of the code
allows for easily adding more queries which do
SELECT COUNT(<whatever>) FROM <whatever>;

Add support for probing process count

See merge request !20

Add Sidekiq monitoring

Closes #3

See merge request !18

Closes #3

Allow returning quantiles for process-related probes

Closes #4

See merge request !19

Closes #4

Vacuum queries are capitalised so we need to match capitalised

We needed to use case-insensitive matcher (ILIKE) beside I've changed the query that we match to be capitalised too because that's how you're going to see them on the server, at least is what I think

Relates to #6

See merge request !17

Include Vacuum Queries collector

Closes #6

See merge request !16

Add documentation for gitlab-monitor

See merge request !15

Combine multiple probers into one



See merge request !13

Fix a typo in a memory field name



See merge request !12

Bind server to 0.0.0.0 address



See merge request !11

Fix DB prober arguments



See merge request !10

Quote `pgrep` arguments



See merge request !9

Monitor process attributes



See merge request !8