tests: don't drop global hgrc
Various tests are failing when the simple store extension is loaded
because the test overrides HGRCPATH and preempts loading of extensions
that were injected via --extra-config-opt.
In most cases, it is acceptable to always load the global HGRCPATH.
So this commit changes a couple of tests so the global HGRCPATH
is still pulled in.
Differential Revision: https://phab.mercurial-scm.org/D3098
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Ran 16 tests in 0.000s
OK