archivers/engrampa: switch to GitHub release asset

Minor versions of 1.28.x are no longer published to the MATE mirror
and are only available on GitHub. Use USE_GITHUB=nodefault with a
release tarball instead of the auto-generated one, as recommended
by the porter's handbook. Remove autoreconf, autoconf-archive,
yelp-tools, and the mate-submodules GH_TUPLE, not needed with
release tarballs.