elasticsearch: Fix indexing blobs and commits with strict mapping on

The elasticsearch index recently gained strict, rather than dynamic,
mapping. However, we're still missing two important fields:

* repository.commit.type
* repository.blob.type

I mistakenly thought all was well, when in fact our Ruby and Go
indexers both silently ignore documents that fail to create.

This fix is sufficient to bring the document count back up to the right
number on my test instance (~262,000 instead of ~2000)

ee/app/models/concerns/elastic/application_search.rb

@@ -145,6 +145,8 @@ module Elastic
 
         ### REPOSITORIES
         indexes :blob do
+          indexes :type, type: :keyword
+
           indexes :id, type: :text,
                        index_options: 'offsets',
                        analyzer: :sha_analyzer
@@ -168,6 +170,8 @@ module Elastic
         end
 
         indexes :commit do
+          indexes :type, type: :keyword
+
           indexes :id, type: :text,
                        index_options: 'offsets',
                        analyzer: :sha_analyzer