abdi_processrepoarglist: hoist conduit creation

Create any required conduits before any workers process repos, this
means the conduit manager does not need to be synchronized between
workers.

Test Plan:
$ ./precommit.sh
phlsys_conduit: multiprocessing instead of thread

Switch to using multiprocessing primitives instead of threading
primitives, threading is broken in Python 2.7.

Test Plan:
$ ./precommit.sh