Fix two small problems on how we handle manual actions

## What does this MR do?
Fixes two small problems in how we handle manual actions:
- On environments page we show a `Play` for the same action that is lately deployed, we should show other actions only
- When we process a pipeline that have only a manual action in a stage, the pipeline will stop being processed.

- Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [ ] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)


See merge request !5366