Follow up from #29082.

This ticket makes sure that installed pc files in SAGE_LOCAL are uninstalled correctly when the installation changes, via the staging/uninstalling mechanism extended to script packages by #29386.

• Code in build/make/Makefile.in is removed in favor of creating one or several new type=script packages, whose spkg-install does the installation to SAGE_LOCAL.

Depends on #29082
Depends on #29386

CC: @dimpase @jhpalmieri

Component: build

Branch/Commit: u/mkoeppe/system_blas_facade @ b493a32

Issue created by migration from https://trac.sagemath.org/ticket/29387