perf: reduce memory usage upon running server tests (#3949)

* perf: reduce memory usage upon running server tests

* perf: plug leaks in server/routes

* perf: plug leaks in server/scripts

* perf: plug leaks in server/policies

* perf: plug leaks in server/models

* perf: plug leaks in server/middlewares

* perf: plug leaks in server/commands

* fix: missing await on db.flush

* perf: plug leaks in server/queues

* chore: remove unused legacy funcs

* fix: await on db.flush

* perf: await on GC to run in between tests

* fix: remove db refs

* fix: revert embeds

* perf: plug leaks in shared/i18n

server/models/User.test.ts

@@ -1,16 +1,21 @@
 import { buildUser, buildTeam, buildCollection } from "@server/test/factories";
-import { flushdb } from "@server/test/support";
+import { getTestDatabase } from "@server/test/support";
 import CollectionUser from "./CollectionUser";
 import UserAuthentication from "./UserAuthentication";
 
-beforeEach(() => flushdb());
+const db = getTestDatabase();
+
 beforeAll(() => {
   jest.useFakeTimers().setSystemTime(new Date("2018-01-02T00:00:00.000Z"));
 });
+
 afterAll(() => {
   jest.useRealTimers();
+  db.disconnect();
 });
 
+beforeEach(db.flush);
+
 describe("user model", () => {
   describe("destroy", () => {
     it("should delete user authentications", async () => {