Add logic to Projects::AllBranchesRule::MergeRequestApprovalSetting to load `prevent_editing_approval_rules`
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In https://gitlab.com/gitlab-org/gitlab/-/issues/504615+ we created a new table and renamed some of the attributes to better suit the new system.
`disable_overriding_approvers_per_merge_request` has been renamed to `prevent_editing_approval_rules` so we need to create a method in `Projects::AllBranchesRule::MergeRequestApprovalSetting` to fetch `project.disable_overriding_approvers_per_merge_request`
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