Blacklist H803
Blacklist H803

H803 isn't supported by community consensus. Blacklist it to avoid
breaking folk's muscle memory.

Change-Id: I8eea9eb2562e12136018e762c8a5e23527fcf48f

varunarya10/diskimage-builder,takahashinobuyuki/diskimage-builder,CSC-IT-Center-for-Science/diskimage-builder,zioproto/diskimage-builder,eantyshev/diskimage-builder,CSC-IT-Center-for-Science/diskimage-builder,openstack/diskimage-builder,NaohiroTamura/diskimage-builder,switch-ch/diskimage-builder,switch-ch/diskimage-builder,takahashinobuyuki/diskimage-builder,citrix-openstack-build/diskimage-builder,rdo-management/diskimage-builder,NaohiroTamura/diskimage-builder,eantyshev/diskimage-builder,zioproto/diskimage-builder,JioCloud/diskimage-builder,rdo-management/diskimage-builder,citrix-openstack-build/diskimage-builder,varunarya10/diskimage-builder,JioCloud/diskimage-builder,openstack/diskimage-builder