test: use bundle2 for exchange in test-largefile
Using bundle2 for exchange unlock the usage of changegroup version 2. This
version of the changegroup held more information (delta base) that result in a
small increase in content size.
It also lead to reordering of output because the exchange scheduling is a bit
different.
Testing that hghave does not crash when checking features
$ "$TESTDIR/hghave" --test-features 2>/dev/null