Fix Rubocop offense and use a symbol instead of a string

app/controllers/projects/pipeline_schedules_controller.rb

@@ -42,7 +42,7 @@ class Projects::PipelineSchedulesController < Projects::ApplicationController
   end
 
   def play
-    limiter = ::Gitlab::ActionRateLimiter.new(action: 'play_pipeline_schedule')
+    limiter = ::Gitlab::ActionRateLimiter.new(action: :play_pipeline_schedule)
 
     if limiter.throttled?(throttle_key, 1)
       flash[:alert] = 'You cannot play this scheduled pipeline at the moment. Please wait a minute.'

lib/gitlab/action_rate_limiter.rb

@@ -16,7 +16,7 @@ module Gitlab
       value = 0
 
       Gitlab::Redis::Cache.with do |redis|
-        cache_key = "action_rate_limiter:#{action.to_s}:#{key}"
+        cache_key = "action_rate_limiter:#{action}:#{key}"
         value = redis.incr(cache_key)
         redis.expire(cache_key, expiry_time) if value == 1
       end