Remove Compute role parameters from overcloud.yaml

Remove Compute role parameters from overcloud.yaml

To enable custom-roles we need to pass these directly into th
role template (where these are already defined with the same
names).  The remaining parameters which will be removed in
subsequent patches, as some will require additional work to
ensure backwards compatibility.

Change-Id: I5a7e4f12aa7b9697086c1e19a4f7fcb24198c1d4
Partially-Implements: blueprint custom-roles