Remove Python build parallelism test

The build was successful with '-j4', but it is not worth chasing for the
complication added to the Puppet configuration.  Will keep an eye on
QEMU changelogs for improvements to qemu-user forking/threading.

Containerfile

@@ -16,8 +16,6 @@ RUN puppet agent --test --certname ci --environment main --tags nest::base::dist
 # it also needs to be persisted in the image.
 ENV LANG=en_US.UTF-8
 
-RUN USE='sqlite' MAKEOPTS="-j4 -l17" emerge -v --oneshot -j1 '=dev-lang/python-3.8.6-r1'
-
 # Switch to desired profile and make the base system consistent with it,
 # breaking out of a possible circular dependency between mesa and libva.
 RUN eselect profile set "nest:${PROFILE}"