App config caching per instance (#3071)

* Do caching of app config per instance instead of across all of them in redis

* Add changes file

* Simplify code based on review comment

* Use go-cache instead of creating our own

* Dont export consts

* Copy app config before returning it

* Fix lint

* Update go sum

* Update go sum

cmd/fleet/serve.go

@@ -252,7 +252,7 @@ the way that the Fleet server works.
 			}
 			level.Info(logger).Log("component", "redis", "mode", redisPool.Mode())
 
-			ds = cached_mysql.New(ds, redisPool)
+			ds = cached_mysql.New(ds)
 			resultStore := pubsub.NewRedisQueryResults(redisPool, config.Redis.DuplicateResults)
 			liveQueryStore := live_query.NewRedisLiveQuery(redisPool)
 			if err := liveQueryStore.MigrateKeys(); err != nil {