FIX: move hp request from /users to /token (#10795)

`hp` is a valid username and we should not prevent users from registering it.

test/javascripts/helpers/create-pretender.js

@@ -416,7 +416,7 @@ export function applyDefaultHandlers(pretender) {
   pretender.post("/u/action/send_activation_email", success);
   pretender.put("/u/update-activation-email", success);
 
-  pretender.get("/u/hp.json", function () {
+  pretender.get("/session/hp.json", function () {
     return response({
       value: "32faff1b1ef1ac3",
       challenge: "61a3de0ccf086fb9604b76e884d75801",

test/javascripts/unit/lib/url-test.js

@@ -59,14 +59,12 @@ QUnit.test("isInternal on subfolder install", (assert) => {
 QUnit.test("userPath", (assert) => {
   assert.equal(userPath(), "/u");
   assert.equal(userPath("eviltrout"), "/u/eviltrout");
-  assert.equal(userPath("hp.json"), "/u/hp.json");
 });
 
 QUnit.test("userPath with prefix", (assert) => {
   setPrefix("/forum");
   assert.equal(userPath(), "/forum/u");
   assert.equal(userPath("eviltrout"), "/forum/u/eviltrout");
-  assert.equal(userPath("hp.json"), "/forum/u/hp.json");
 });
 
 QUnit.test("routeTo with prefix", async (assert) => {