Backport splitting approval changes from CE

Igor Drozdovrequested to merge
id-split-self-approval-restrictions into master

What does this MR do?

Backport splitting approval changes from CE

Author and committers approvals are split in EE This commit provides backports for those changes

EE MR: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/10234

What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ee/issues/10441

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