Remove unused oslo.config import

Commit 46e88320e6e6231550f3e2b40312c51f55e059f5 added
the oslo.config import in one of it's patch series but
in the revision that was ultimately merged, the import
was no longer used - but we forgot to remove the import.

This cleans that up.

Change-Id: I3fcfdab625be68a19162b5053ad4f6f180a72a4d
Merge "Remove unused oslo.config import"