tests: blacklist a handful of test with rhg or chg

The use of alias to enforce chg and rhg means we are actually using a mix
of rhg/chg and hg when calling hg in the test. Fixing this breaks
various tests. This would be a large detour to fix that. I am disabling
them for now with an appropriate comment.

We would hopefully get back to them by the 5.8 release.

Differential Revision: https://phab.mercurial-scm.org/D11052