Remove shadow file #ifdef content from non oslo-aero code base

[mvertens]

Issue Type

Code Clean-up

Issue Description

The current implementation of shadow files unfortunately also populated the original non-shadow file code with the #ifdefs of the shadow files. This needs to be undone and all the changes should be solely contained in the shadow files in src_cam in the oslo_aero code base.

Will this change answers?

No

Will you be implementing this yourself?

Yes

[oyvindseland]

Question on status: The remaining ifdef now is the ifdef AEROCOM that should be replaced by namelist?
--> Likely too late for 2.3.0, but can still be done for 2.3.1 ? @mvertens

[gold2718]

The only ifdef AEROCOM left is in cam_diagnostics which is still there even in noresm_development.