tests: remove lz4 as dependency while running tests

One of the previous patch authored by Augie rips out the lz4 dependency and
things should work without it.

Now there are just 2-3 tests failing because of same change in emitrevisions()
API.

Differential Revision: https://phab.mercurial-scm.org/D5192

tests/remotefilelog-library.sh

@@ -1,5 +1,3 b''
-${PYTHON:-python} -c 'import lz4' || exit 80
-
 CACHEDIR=$PWD/hgcache
 cat >> $HGRCPATH <<EOF
 [remotefilelog]