Add mock identity provider for serverless (2nd attempt) (#171513)

Attempting to merge #170852 again now that the release artefact step has
been fixed as part of https://github.com/elastic/kibana/pull/171457

---------

Co-authored-by: kibanamachine <42973632+kibanamachine@users.noreply.github.com>
Co-authored-by: Aleh Zasypkin <aleh.zasypkin@gmail.com>
Co-authored-by: Dzmitry Lemechko <dzmitry.lemechko@elastic.co>

scripts/es.js

@@ -20,6 +20,7 @@ kbnEs
     'source-path': resolve(__dirname, '../../elasticsearch'),
     'base-path': resolve(__dirname, '../.es'),
     ssl: false,
+    kibanaUrl: 'https://localhost:5601/',
   })
   .catch(function (e) {
     console.error(e);