Fix inefficient queries in “Follows and followers” as well as several admin pages (#27116)

app/models/relationship_filter.rb

@@ -60,13 +60,13 @@ class RelationshipFilter
   def relationship_scope(value)
     case value
     when 'following'
-      account.following.eager_load(:account_stat).reorder(nil)
+      account.following.includes(:account_stat).reorder(nil)
     when 'followed_by'
-      account.followers.eager_load(:account_stat).reorder(nil)
+      account.followers.includes(:account_stat).reorder(nil)
     when 'mutual'
-      account.followers.eager_load(:account_stat).reorder(nil).merge(Account.where(id: account.following))
+      account.followers.includes(:account_stat).reorder(nil).merge(Account.where(id: account.following))
     when 'invited'
-      Account.joins(user: :invite).merge(Invite.where(user: account.user)).eager_load(:account_stat).reorder(nil)
+      Account.joins(user: :invite).merge(Invite.where(user: account.user)).includes(:account_stat).reorder(nil)
     else
       raise "Unknown relationship: #{value}"
     end