Tighten the order values of marketplace demos

Re-number the order values of marketplace demos so that they are consecutive starting at 1, preserving their relative ordering. For example, demos with order=[1, 5, 20] become [1, 2, 3]. Demos with order=null are left untouched.

Required scopes (any one):

• air:sre (roles: air_sre)
• air:admin (roles: air_admin)