Resolve GraphQL/ResolverMethodLength in StageType

Arpit Tripathirequested to merge
gitlab-community/gitlab-org/gitlab:fix/rubocop-resolver-method-length into master

## What does this MR do?

This MR resolves a `GraphQL/ResolverMethodLength` RuboCop offense in `app/graphql/types/ci/stage_type.rb`.


fixes #592383 (closed)

Merge request reports