MM-11243: Make Elasticsearch work after enabling without restart. (#9146)

* MM-11243: Make Elasticsearch work after enabling without restart.

* Also cope with config vars changing whilst enabled.

einterfaces/elasticsearch.go

@@ -11,6 +11,7 @@ import (
 
 type ElasticsearchInterface interface {
 	Start() *model.AppError
+	Stop() *model.AppError
 	IndexPost(post *model.Post, teamId string) *model.AppError
 	SearchPosts(channels *model.ChannelList, searchParams []*model.SearchParams) ([]string, model.PostSearchMatches, *model.AppError)
 	DeletePost(post *model.Post) *model.AppError