Bench: Update CheckBroadcast Cron defaults

When we create a broadcast, a checkbroadcast cron is automatically created to poll the oceanTV service. The default for the cron is now set to ```https://tv.cloudblue.org```. However, the cron lit element (```cmd/oceanbench/ts/cron-settings.ts```) still uses the old value of ```oceantv.appspot.tv```.

Whilst this still it works, it means that the cron element does not detect that the production cron has been selected, and displays "other" indicating that a non-standard endpoint is being used.