rust-dirstate-status: add call to rust-fast path for `dirstate.status`
The reasoning behind this patch is explained in the first patch of the series.
Differential Revision: https://phab.mercurial-scm.org/D7060
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# Avoid interference from actual test env:
unset HGTEST_JOBS
unset HGTEST_TIMEOUT
unset HGTEST_PORT
unset HGTEST_SHELL