Housekeeping: Locator GetAllRegistrations against different DI

[dpvreony]

There is a method associated with GetAllRegistrations too that might need some testing around for the various DI engines to make sure they work as we expect.

_Originally posted by @glennawatson in https://github.com/render_node/MDIzOlB1bGxSZXF1ZXN0UmV2aWV3VGhyZWFkMTg2NDYzNjUwOnYy/pull_request_review_threads/discussion

Split out into new issue as it got lost in the review comments for #360 so I had to hunt it out :)