Reduce overhead and optimize ProjectTeam#max_member_access performance

The previous implementation would load the entire team member list and their
respective attributes. Now we only search for the user's specific
access level.

In gitlab-com/operations#42, this reduces the overall overhead of rendering
the issue from 28% to 20%.

First step of optimizing #19273

CHANGELOG

@@ -26,6 +26,7 @@ v 8.9.3 (unreleased)
   - Fix encrypted data backwards compatibility after upgrading attr_encrypted gem
   - Update mobile button icons to be more inline with typical UI paradigms
   - Fixes missing avatar on system notes. !4954
+  - Improve performance of obtaining the maximum access of a user in a project
 
 v 8.9.2
   - Fix visibility of snippets when searching.

app/models/member.rb

@@ -32,6 +32,7 @@ class Member < ActiveRecord::Base
   scope :request, -> { where.not(requested_at: nil) }
   scope :non_request, -> { where(requested_at: nil) }
   scope :non_pending, -> { non_request.non_invite }
+  scope :has_access, -> { where('access_level > 0') }
 
   scope :guests, -> { where(access_level: GUEST) }
   scope :reporters, -> { where(access_level: REPORTER) }

app/models/project_team.rb

@@ -137,20 +137,10 @@ class ProjectTeam
   def max_member_access(user_id)
     access = []
 
-    project.members.non_request.each do |member|
-      if member.user_id == user_id
-        access << member.access_field if member.access_field
-        break
-      end
-    end
+    access += project.members.non_request.where(user_id: user_id).has_access.pluck(:access_level)
 
     if group
-      group.members.non_request.each do |member|
-        if member.user_id == user_id
-          access << member.access_field if member.access_field
-          break
-        end
-      end
+      access += group.members.non_request.where(user_id: user_id).has_access.pluck(:access_level)
     end
 
     if project.invited_groups.any? && project.allowed_to_share_with_group?