Update ES client to 7.13.3, deprecate _type

.gitlab/ci/global.gitlab-ci.yml

.gitlab/ci/rails.gitlab-ci.yml

.gitlab/ci/rules.gitlab-ci.yml

GITLAB_ELASTICSEARCH_INDEXER_VERSION

Gemfile

Gemfile.lock

config/initializers/elastic_client_setup.rb

ee/lib/elastic/latest/config.rb

ee/lib/elastic/latest/custom_language_analyzers.rb

ee/lib/elastic/latest/issue_config.rb

ee/lib/elastic/latest/merge_request_config.rb

ee/lib/elastic/latest/note_config.rb

...tensions/elasticsearch/model/indexing/instance_methods.rb

ee/lib/gitlab/elastic/helper.rb

ee/spec/lib/ee/gitlab/elastic/helper_spec.rb

ee/spec/lib/elastic/latest/config_spec.rb

ee/spec/lib/elastic/latest/custom_language_analyzers_spec.rb

ee/spec/lib/elastic/latest/issue_config_spec.rb

ee/spec/lib/elastic/latest/merge_request_config_spec.rb

ee/spec/lib/elastic/latest/note_config_spec.rb