Revert "Merge branch '50559-add-milestone-progress-to-api' into 'master'"
When https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/25173 was merged to EE, the EE specs exposed some N+1 queries in Milestoneish#percent_complete
. For each milestone, this calls IssuesFinder#execute
. This needs to be optimized.