This is so that users can get installation hints e.g. for homebrew after running conda deactivate
(as for example advised by the Anaconda detection code added by #27699)

CC: @isuruf @jhpalmieri @dimpase @slel

Component: build: configure

Author: Matthias Koeppe

Branch/Commit: 27f6bac

Reviewer: Isuru Fernando

Issue created by migration from https://trac.sagemath.org/ticket/29560