Add metrics of redundant `github_repo_stat` rows

[iakunin]

Add metrics for the following query:

select grs.github_repo_id, grs.type, count(grs.id) from github_repo_stat grs
where grs.id not in (
    select forks_up_result.github_repo_stat_id from forks_up_result
) and grs.id not in (
    select stars_up_result.github_repo_stat_id from stars_up_result
) and grs.id not in (
    select too_many_stars_result.github_repo_stat_id from too_many_stars_result
) and grs.id not in (
    select too_small_result.github_repo_stat_id from too_small_result
)
group by grs.github_repo_id, grs.type
having count(grs.id) > 2
order by count(grs.id) desc