Disabling professor from accidentally downgrading themselves should not prevent Admin from upgrading themself

[ngwattcos]

Required Functionality

Professor should not be able to downgrade themself to TA or Student.

Actual Functionality

The dropdown for "[email protected]" is disabled for the user "user". This prevents the Admin from upgrading themselves for testing purposes.

Actual Fix

The dropdown should only disable (or hide) the "TA" or "Student" dropdown if the user is a professor (the simpler logic above skips the edge case where the user is an admin trying to upgrade themselves)