Make local git dir creation optional

manage-projects unconditionally set up a local git dir even if the
config option was unset. We change that behavior because new gerrit url
paths make a local git dir option less straight forward. If you've set a
git dir path we'll continue to honor it, otherwise this step is skipped.

Depends-On: https://review.opendev.org/762196
Change-Id: I39ef5ba7cd8747d52487cb0252a9b12878d6247b
1 file changed