Create Redisable#redis (#9633)

* Create Redisable

* Use #redis instead of Redis.current

app/lib/potential_friendship_tracker.rb

@@ -11,6 +11,8 @@ class PotentialFriendshipTracker
   }.freeze
 
   class << self
+    include Redisable
+
     def record(account_id, target_account_id, action)
       return if account_id == target_account_id
 
@@ -31,11 +33,5 @@ class PotentialFriendshipTracker
       return [] if account_ids.empty?
       Account.searchable.where(id: account_ids)
     end
-
-    private
-
-    def redis
-      Redis.current
-    end
   end
 end