Remove translation from step_script to build_script in custom executor
### Overview
Remove the translation added in https://gitlab.com/gitlab-org/gitlab-runner/-/merge_requests/2227 / https://gitlab.com/gitlab-org/gitlab-runner/-/issues/26418 for "step_script" to "build_script".
Custom executors would need to accept dynamically generated stage names, e.g. "step_script", "step_release".
Additionally, some translation happens in gitlab rails and needs to be cleaned up too. See https://gitlab.com/gitlab-org/gitlab/-/merge_requests/42010
The follow stage is going to be renamed:
| old stage name | new stage name (14.0) |
|-|-|
| `build_script` | `step_script` |
issue