default=None is unneeded in config definitions

It's not required for setting config options, as it's the default, and
there were only 2 final places where it was set in the code, so we
should just clear that out.

Change-Id: I33dd0c002e48a5f5d26047b7f87643fce67f9e64
Closes-Bug: #1323975
Merge "default=None is unneeded in config definitions"