Pick revert of `require-all-templates-to-include-default-stages'

What does this MR do?

This picks the https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/26954 reverted as part of https://gitlab.com/gitlab-org/gitlab-ce/issues/60106

Resolves https://gitlab.com/gitlab-org/gitlab-ce/issues/60106

Does this MR meet the acceptance criteria?

Conformity

• Code review guidelines
• Style guides