Skip portage upgrade

Seems like updating just portage after the profile change can lead to
slot conflicts.  Must evaluate entire @world.

Containerfile

@@ -16,7 +16,7 @@ COPY --from=nest-overlay / /var/db/repos/nest/
 
 # Update, then rebuild all packages using a custom profile
 RUN eselect profile set "nest:${PROFILE}"
-RUN emerge --info && emerge -v --oneshot sys-apps/portage && emerge --info
+RUN emerge --info
 RUN emerge -v --update --deep --newuse --with-bdeps=y @world
 RUN emerge --depclean
 RUN emerge -v --emptytree @world