♻️ Refactor time related namespaces

Mainly removes the custom app.util.time namespace
from frontend and backend and normalize all to use
the app.common.time namespace

backend/test/backend_tests/tasks_telemetry_test.clj

@@ -7,7 +7,6 @@
 (ns backend-tests.tasks-telemetry-test
   (:require
    [app.db :as db]
-   [app.util.time :as dt]
    [backend-tests.helpers :as th]
    [clojure.pprint :refer [pprint]]
    [clojure.test :as t]