Remove service from ServiceListenerFactory

- Point of original PR that broke BC was to remove the requirement of
  ext-intl by default. Adding the TranslatorInterface as a service by
  default breaks this. Removed, and we can now document it.
Added note to README

- Covers #5406, and the changes also present in this PR.
More BC fixes

- Check for each of MvcTranslator, Translator, and TranslatorInterface
  in order to perform injections.
- Since "Translator" is usually an alias of "MvcTranslator", check this last.