Dockerfile: sort FEATURES, drop USE

Dockerfile

@@ -5,9 +5,9 @@ COPY --from=portage /var/db/repos/gentoo /var/db/repos/gentoo
 
 ENV ACCEPT_KEYWORDS="~amd64" \
     EMERGE_DEFAULT_OPTS="--jobs=4 --quiet" \
-    FEATURES="-sandbox -usersandbox -ipc-sandbox -network-sandbox -mount-sandbox -pid-sandbox" \
+    FEATURES="-sandbox -usersandbox -ipc-sandbox -mount-sandbox -network-sandbox -pid-sandbox" \
     MAKEOPTS="-j4" \
-    USE="-perl -ipc -rsync-verify"
+    USE=""
 
 RUN emerge dev-vcs/git app-portage/repoman dev-util/pkgcheck \
  && rm -rf /var/cache/distfiles/*