Remove standard token filter to work with ES7

According to the docs at
https://www.elastic.co/guide/en/elasticsearch/reference/current/breaking-changes-7.0.html#standard-filter-removed
and
https://www.elastic.co/guide/en/elasticsearch/reference/6.8/analysis-standard-tokenfilter.html#analysis-standard-tokenfilter
this does not actually do anything so we should just remove it.

ee/lib/elastic/latest/config.rb

@@ -21,7 +21,7 @@ module Elastic
             analyzer: {
               default: {
                 tokenizer: 'standard',
-                filter: %w(standard lowercase my_stemmer)
+                filter: %w(lowercase my_stemmer)
               },
               my_ngram_analyzer: {
                 tokenizer: 'my_ngram_tokenizer',