Minor, remove redundant updates in huge diff tests

This makes the tests ~6 seconds shorter on tested machine.

Test Plan: $ ./precommit.sh
Move Arcyd author query to new conduit

Replace direct dependencies on phlsys_conduit with the
abdt_conduit abstraction.

Test Plan: $ ./precommit.sh
Remove redundant conduit query

Conduit calls are expensive, remove a query with an unused result.

Test Plan $ ./precommit.sh
Move Arcyd 'accepted' query to new conduit

Replace direct dependencies on phlsys_conduit with the
abdt_conduit abstraction.

Test Plan: $ ./precommit.sh
Move Arcyd 'close revision' to new conduit

Replace direct dependencies on phlsys_conduit with the
abdt_conduit abstraction.

Test Plan: $ ./precommit.sh
Move Arcyd 'create empty revision' to new conduit

Replace direct dependencies on phlsys_conduit with the
abdt_conduit abstraction.

Test Plan: $ ./precommit.sh
Move Arcyd 'get_commit_message' to new conduit

Replace direct dependencies on phlsys_conduit with the
abdt_conduit abstraction.

Test Plan: $ ./precommit.sh
Arcyd: remove redundant act_as_user_context

Remove a redundant act_as_user_context, this allows us to unsplit some
lines due to the new indentation level.

Test Plan: $ ./precommit.sh
Move last Arcyd as_user context to new conduit

Replace direct dependencies on phlsys_conduit with the
abdt_conduit abstraction.

Test Plan: $ ./precommit.sh
Move Arcyd tests to use new conduit

Update abdi_processrepo__t to use abdt_conduit.Conduit so that we will
later be able to swap it for a mock implementation; the tests will be
much more scalable.

Test Plan: $ ./precommit.sh
Move Arcyd completely over to new conduit

Finish replacing direct usage of phlsys_conduit with the abstract
abdt_conduit.

Test Plan: $ ./precommit.sh
Minor, sort imports in abdi_processrepo__t
WIP: conduitmock
WIP: abdt_git
fixup! WIP: abdt_git
Arcyd: inject git object into processrepo

So that we can gradually replace direct dependence on phlsys_git with an
abstraction; inject the required git object into process repo instead of
just the path.

Take the opportunity to consolidate some of the test code in
abdi_processrepo__t which creates git objects.

Test Plan: $ ./precommit.sh