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.
Ancestors of 5
4 2 0
Ancestors of 6 and 5
3 4 2 1 0
Ancestors of 5 and 4
4 2 0
Ancestors of 7, stop at 6
6
Ancestors of 7, including revs
7 6 5 3 4 2 1 0
Ancestors of 7, 5 and 3, including revs
7 5 3 6 4 2 1 0
Descendants of 5
7 8
Descendants of 5 and 3
6 7 8
Descendants of 5 and 4
5 7 8