Follow up from PLANET-5285

Make the “Goal” field mandatory and display a placeholder — Select Goal — on the dropdown? (eg. the first three requirements on this ticket's description)

It’s still displaying “Petition Signup” as a selected option in the backend, even though the value is not set... The current behaviour might be confusing for the editor since it seems there's a value already selected.

Tasks

• "Goal" field should be mandatory
• Display — Select Goal — as the placeholder