[Users] fix WeylScal4::teukolskyID testsuite

Hello all,

Ian Hinder found that the testsuite teukolskyID for WeylScal4 was poisoned. It turns out I had forgotten to add MoL to the list of ActiveThorns in the testsuite.

Attached please find a patch which rectifies that. Ok to apply (both development and release branch)?

Expect some more patches while Tanja and I try and add some extra statements to WeylScal4 to make sure MoL is present (ie. something like inherit from MoL maybe) and adapt to a possible future change in how MoL_PseudoEvolution is scheduled.

Ian also pointed out some issues with how (outer hopefully) boundaries are handled which will have to be looked at eventually.

Yours, Roland