Reset childjobs watcher when kicking it off from a new parent job route (#24668)

.changelog/24668.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+ui: Fix an issue where 2 parent jobs would see the others dispatches if it were otherwise empty
+```

ui/app/controllers/jobs/job/index.js

@@ -98,6 +98,7 @@ export default class IndexController extends Controller.extend(
     { id, namespace },
     throttle = Ember.testing ? 0 : 2000
   ) {
+    this.childJobs = [];
     while (true) {
       let params = {
         filter: `ParentID == "${id}"`,