Remove unused gitlab_pg_sequences_saturation_ratio

See merge request !213



Merged-by: Ahmad Sherif <ahmad@gitlab.com>
Approved-by: Leonardo da Rosa <ldarosa@gitlab.com>
Approved-by: Ahmad Sherif <ahmad@gitlab.com>
Co-authored-by: Maxime Orefice <morefice@gitlab.com>

Previously adding the `users` entry in the
`database.rows_count.selected_queries` configuration would return no
new data. This was happening because there was a `WHERE user_type IS
NULL` query that caused no rows to match.

Since GitLab 16.0, all human users now have a `user_type` of 0 instead
of NULL:
gitlab-org/gitlab!115849.

Adjust the query to match the schema.

Relates to
#109

Fix users selected queries not returning any data

See merge request !214



Merged-by: Ahmad Sherif <ahmad@gitlab.com>
Approved-by: Ahmad Sherif <ahmad@gitlab.com>
Co-authored-by: Stan Hu <stanhu@gmail.com>

feat: change content type

See merge request !211



Merged-by: Ahmad Sherif <ahmad@gitlab.com>
Approved-by: Stan Hu <stanhu@gmail.com>
Co-authored-by: ngnix <klimov9129@gmail.com>

Bump version to v15.2.0

See merge request !215



Merged-by: Ahmad Sherif <ahmad@gitlab.com>
Approved-by: Stan Hu <stanhu@gmail.com>