lfs: remove internal url in test `test-lfs-test-server.t` refers to a FB internal domain and requires certain implementation (ex. set error code to 404) at that endpoint. Without any workaround, It should in theory error out like "Domain cannot be resolved". I don't know how Matt Harbison ran the test. This patch changes the test to only depend on `lfs-test-server`. Unfortunately the logic has to be changed since `lfs-test-server` does not set error code to 404 but just removes "download" from "actions". Differential Revision: https://phab.mercurial-scm.org/D1849