Follow-up from "Add milestones to release blocks": Visual cleanup when no milestones are associated to a release

The following discussion from gitlab-ce!32765 should be addressed:

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

  @nfriend I know this is not related to this MR, but since we're at this area, I think we might want to create a follow-up issue on the following at least.

  When we do have at least one Milestone associated with a release, things look very slick. However, when a release does not have an associated Milestone, the things look a bit odd in terms of paddings around that middle dot separator: too much on the left of it comparing to the right.

  @nfriend feel free to resolve this discussion by creating a follow-up issue.

  

  /cc @rverissimo