tests: remove initial bundle2 enabling in various bundle2 tests Bundle 2 is enable by default since 3.6 so we don't need this anymore. The remaining use of 'experimental.bundle2-exp' are there to test legacy behavior with bundle 1. Future patches will introduce a way outside of experimental to test that.

tests: remove bundle2 activation from test-largefiles.t This is an old config that predate bundle2 on by default. This should have been remove after Mercurail 3.6 got released.