Remove the distinction between project creators and drone operators

[spwoodcock]

• This could be kept on the backend and added back in when needed.
• But practically for now, it makes no difference at all which type of user is selected.
• It simply confuses users during sign up.
• The page could be removed entirely and all users created as project manager role for now (otherwise they won't be able to modify projects).

[linear]

TECH-1223