infinitepush: drop logic related to treemanifest extension
treemanifest is another facebook's extension which is not in core. Let's drop
the logic related to infinitepush extension which is now ported to core.
Differential Revision: https://phab.mercurial-scm.org/D2106
Run Mercurial tests with Vagrant:
$ vagrant up
$ vagrant ssh -c ./run-tests.sh