Plan for extending archived builds

The following discussion from gitlab-ce!22538 should be addressed:

• @grzesiek started a discussion: (+1 comment)

  I still wonder if we should have ci_build.archived flag. It would be much easier to track builds like this in the database.

Proposal

Add database column ci_builds.archived (or degenerated??) to indicate that build is no longer usable for the purpose of being run by Runner, thus retried and played.

The ci_builds.archived column would be used for presenting information on gitlab-ce~3412464 but also as an aid for quickly figuring out the builds to be removed.