abdi_processargs: remove irrelevant comments
abdi_processargs: refactor, use abdt_tryloop

Instead of using phlsys_tryloop directly to retry connecting to Conduit
and fetch from Git, re-use the new abdt_tryloop for these things.

Test Plan:
$ ./precommit.sh
$ ./testbed/arcyd/acceptance_tests.sh
abdi_processargs: refactor, split fetch & connect

Test Plan: $ ./precommit.sh