Follow-up from notifications: improve setup for interactive tests

The following discussion from !214 (merged) should be addressed:

• @sebkur started a discussion: (+10 comments)

  What was your motivation for these changes here?

This discussion was about RunWithMultipleTemporaryAccounts and moving the customization into a LaunchedEffect() with delay(500) in 107100ad:

        application {
            LaunchedEffect(Unit) {
                delay(500)

                apps.forEach {
                    val accountManager = it.getAccountManager()
                    val lifecycleManager = it.getLifecycleManager()
                    val dbKey = accountManager.databaseKey ?: throw AssertionError()
                    lifecycleManager.startServices(dbKey)
                    lifecycleManager.waitForStartup()
                }

                customization(apps)
            }