Reduce differences in spec/support/webmock.rb

Signed-off-by: Rémy Coutable <remy@rymai.me>

spec/support/webmock.rb

 require 'webmock'
 require 'webmock/rspec'
 
-WebMock.disable_net_connect!(allow_localhost: true)
+def webmock_allowed_hosts
+  %w[elasticsearch registry.gitlab.com-gitlab-org-test-elastic-image].tap do |hosts|
+    if ENV.key?('ELASTIC_URL')
+      hosts << URI.parse(ENV['ELASTIC_URL']).host
+    end
+  end.uniq
+end
+
+WebMock.disable_net_connect!(allow_localhost: true, allow: webmock_allowed_hosts)