Fix various warnings from tests

• Things that needed to be wrapped in act are now wrapped in act.
• Things that were wrapped more tan once in act, no longer are.

frontend/src/routes/guest/register/steps/register.test.tsx

@@ -2,6 +2,8 @@ import { render, screen, waitFor } from 'test-utils'
 import AdapterDateFns from '@mui/lab/AdapterDateFns'
 import { LocalizationProvider } from '@mui/lab'
 import { addYears } from 'date-fns/fp'
+import { act } from 'react-dom/test-utils'
+
 import { FeatureContext } from 'contexts'
 import GuestRegisterStep from './register'
 import { GuestRegisterData } from '../enteredGuestData'
@@ -335,10 +337,7 @@ test('Guest not allowed to proceed in wizard if phone number is not valid', asyn
     </FeatureContext.Provider>
   )
 
-  reference.current?.doSubmit()
-
-  // TODO It is stupid to wait like this, but I have not found a wait-for function in jest
-  await new Promise((r) => setTimeout(r, 500))
+  await act(async () => reference.current?.doSubmit())
 
   expect(nextHandler.mock.calls.length).toBe(0)
 })
@@ -389,10 +388,7 @@ test('Guest allowed to proceed in wizard if data is valid', async () => {
     </FeatureContext.Provider>
   )
 
-  reference.current?.doSubmit()
-
-  // TODO It is stupid to wait like this, but I have not found a wait-for function in jest
-  await new Promise((r) => setTimeout(r, 500))
+  await act(async () => reference.current?.doSubmit())
 
   expect(nextHandler.mock.calls.length).toBe(1)
 })