Add cold-start follow recommendations (#15945)

app/lib/potential_friendship_tracker.rb

@@ -28,10 +28,14 @@ class PotentialFriendshipTracker
       redis.zrem("interactions:#{account_id}", target_account_id)
     end
 
-    def get(account_id, limit: 20, offset: 0)
-      account_ids = redis.zrevrange("interactions:#{account_id}", offset, limit)
-      return [] if account_ids.empty?
-      Account.searchable.where(id: account_ids)
+    def get(account, limit)
+      account_ids = redis.zrevrange("interactions:#{account.id}", 0, limit)
+
+      return [] if account_ids.empty? || limit < 1
+
+      accounts = Account.searchable.where(id: account_ids).index_by(&:id)
+
+      account_ids.map { |id| accounts[id.to_i] }.compact
     end
   end
 end