GitLabCI: Allow to remove builds

I have just configurated some builds, and obviously i have done some errors so several builds failed. It would be nice to allow remove builds (one by one, or with multiselect) so to maintain a clean build history

Added feature proposal ~19173 labels

Ref: https://gitlab.com/gitlab-org/gitlab-ce/issues/3421, https://gitlab.com/gitlab-org/gitlab-ce/issues/3439

It looks like this is a duplicate, so closing it in favor of https://gitlab.com/gitlab-org/gitlab-ce/issues/3421

Status changed to closed