sage.doctest.control, sage_setup: Do not check versions of installed packages

[mkoeppe]

For a long time now, the Makefile ensures that packages are automatically reinstalled when the version in build/pkgs/SPKG/package-version.txt changes.

Thus we now remove the check whether the installed package version is current from sage.doctest.control and sage_setup (ex OptionalExtension code).

This simplifies the code, and in particular removes the direct reading of build/pkgs/ from sagelib.

CC: @dimpase @jhpalmieri @kiwifb

Component: build

Keywords: sd111

Branch: u/mkoeppe/sage_doctest_control__sage_setup__do_not_check_versions_of_installed_packages

Issue created by migration from https://trac.sagemath.org/ticket/30848

[mkoeppe]

Branch: u/mkoeppe/sage_doctest_control__sage_setup__do_not_check_versions_of_installed_packages

[mkoeppe]

comment:2

Hoping we can make progress on this ticket this week - https://wiki.sagemath.org/days111

[mkoeppe]

Changed keywords from none to sd111

[mkoeppe]

comment:3

Setting new milestone based on a cursory review of ticket status, priority, and last modification date.

[mkoeppe]

Completed in #37857