rhg: Enable `rhg status` in most tests This subcommand is disabled by default because of bugs that make some test fail. Enable it in the rest of the tests in order to avoid regressing them. As with `RHG_ON_UNSUPPORTED`, an environment variable is used instead of a configuration file and `HGRCPATH` because some tests override `HGRCPATH`. Running `unset RHG_STATUS` at the start of a test restores the default of `rhg status` being disabled. Hopefully it can be increasingly removed from test files as bugs are fixed. Differential Revision: https://phab.mercurial-scm.org/D11756