[REF] web: adapt uncorrect onchange test

In previous commit (https://github.com/odoo/odoo/pull/119214),
this line was added to make the block onchange and check
if the view was rerendered correctly,
but having `await nextTick()` inside an RPC doesn't make sense.
So we use `makeDeferrer()` which is the tool provided for that matter.

closes odoo/odoo#122110

X-original-commit: a1056b1299f1edae736ea1ac00b6895e1c758104
Signed-off-by: Georis François (fge) <fge@odoo.com>

addons/web/static/tests/views/list_view_tests.js

@@ -18592,6 +18592,7 @@ QUnit.module("Views", (hooks) => {
     });
 
     QUnit.test("x2many onchange, check result", async function (assert) {
+        const def = makeDeferred();
         serverData.models.foo.onchanges = {
             m2m: function () {},
         };
@@ -18607,7 +18608,7 @@ QUnit.module("Views", (hooks) => {
             async mockRPC(route, args) {
                 if (args.method === "onchange") {
                     assert.step("onchange");
-                    await nextTick();
+                    await def;
                     return { value: { m2o: [3, "Value 3"] } };
                 }
             },
@@ -18626,6 +18627,9 @@ QUnit.module("Views", (hooks) => {
 
         assert.verifySteps(["onchange"]);
         await click(target.querySelector(".o_list_button_save:not(.btn-link)"));
+        def.resolve();
+        await nextTick();
+
         assert.strictEqual(
             target.querySelector(".o_data_cell.o_many2many_tags_cell").textContent,
             "Value 1Value 2Value 3"