attempt to fix timing problem between async-pipe and ngInit **unfinished**

src/app/group-monitor/group-monitor.component.html

src/app/group-monitor/test-view/test-view.component.html

src/app/group-monitor/test-view/test-view.component.spec.ts

src/app/group-monitor/test-view/test-view.component.ts

src/app/group-monitor/websocket-backend.service.ts