Remove ci_builds.commands dependency

As of release 13.10, gitlab-exporter is throwing an error:

web_1  | ==> /var/log/gitlab/postgresql/current <==
web_1  | 2021-03-22_16:11:42.28050 ERROR:  column ci_builds.commands does not exist at character 825
web_1  | 2021-03-22_16:11:42.28054 STATEMENT:  SELECT
web_1  | 2021-03-22_16:11:42.28054        subquery.namespace_id,
web_1  | 2021-03-22_16:11:42.28055        subquery.shared_runners_enabled,
web_1  | 2021-03-22_16:11:42.28055        subquery.project_id,
web_1  | 2021-03-22_16:11:42.28055        subquery.status,
web_1  | 2021-03-22_16:11:42.28056        MAX(subquery.count) as count
web_1  | 2021-03-22_16:11:42.28056      FROM (
web_1  | 2021-03-22_16:11:42.28056        SELECT

web_1  | 2021-03-22_16:11:42.28056          projects.namespace_id,
web_1  | 2021-03-22_16:11:42.28057          projects.shared_runners_enabled,
web_1  | 2021-03-22_16:11:42.28057          ci_builds.project_id,
web_1  | 2021-03-22_16:11:42.28057          ci_builds.commit_id,
web_1  | 2021-03-22_16:11:42.28057          ci_builds.status,
web_1  | 2021-03-22_16:11:42.28058          COUNT(*) AS count
web_1  | 2021-03-22_16:11:42.28058        FROM ci_builds
web_1  | 2021-03-22_16:11:42.28058        JOIN projects
web_1  | 2021-03-22_16:11:42.28059          ON projects.id = ci_builds.project_id
web_1  | 2021-03-22_16:11:42.28059        JOIN namespaces
web_1  | 2021-03-22_16:11:42.28059          ON namespaces.id = projects.namespace_id
web_1  | 2021-03-22_16:11:42.28059        WHERE ci_builds.type = 'Ci::Build'
web_1  | 2021-03-22_16:11:42.28060          AND ci_builds.status IN ('running', 'pending')
web_1  | 2021-03-22_16:11:42.28060        -- The created_at filter has been introduced for performance reasons only
web_1  | 2021-03-22_16:11:42.28060        AND ci_builds.created_at > NOW() - INTERVAL '7 days'
web_1  | 2021-03-22_16:11:42.28061        GROUP BY
web_1  | 2021-03-22_16:11:42.28061          projects.namespace_id,
web_1  | 2021-03-22_16:11:42.28061          projects.shared_runners_enabled,
web_1  | 2021-03-22_16:11:42.28061          ci_builds.project_id,
web_1  | 2021-03-22_16:11:42.28062          ci_builds.commit_id,
web_1  | 2021-03-22_16:11:42.28062          ci_builds.status,
web_1  | 2021-03-22_16:11:42.28062          ci_builds.commands
web_1  | 2021-03-22_16:11:42.28062        HAVING COUNT(*) > 2
web_1  | 2021-03-22_16:11:42.28063      ) AS subquery
web_1  | 2021-03-22_16:11:42.28063      GROUP BY
web_1  | 2021-03-22_16:11:42.28063        subquery.namespace_id,
web_1  | 2021-03-22_16:11:42.28064        subquery.shared_runners_enabled,
web_1  | 2021-03-22_16:11:42.28065        subquery.project_id,
web_1  | 2021-03-22_16:11:42.28065        subquery.commit_id,
web_1  | 2021-03-22_16:11:42.28065        subquery.status
web_1  | 2021-03-22_16:11:42.28066
web_1  |
web_1  | ==> /var/log/gitlab/gitlab-exporter/current <==
web_1  | 2021-03-22_16:11:42.28078 E, [2021-03-22T16:11:42.280683 #992] ERROR -- : Error connecting to the database: ERROR:  column ci_builds.commands does not exist
web_1  | 2021-03-22_16:11:42.28082 LINE 30:     ci_builds.commands
web_1  | 2021-03-22_16:11:42.28083              ^
web_1  | 2021-03-22_16:11:42.28083
web_1  | 2021-03-22_16:11:42.49100 127.0.0.1 - - [22/Mar/2021:16:11:42 UTC] "GET /database HTTP/1.1" 200 1420
web_1  | 2021-03-22_16:11:42.49104 - -> /database

This error is caused by removal of the commands column via this migration.