Remove tools/valgrind/shard-all-tests.sh

This seems unused, hasn't been updated in years, still talks about hammer and
uses make on Linux etc.

BUG=294387
R=thestig@chromium.org

Review URL: https://codereview.chromium.org/31153002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229710 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 229710