netebpfext - user mode mock for wfp - Sublayer doesn't need to track state

Currently the netebpfext's WFP mock tracks state for FWPM_SUBLAYERs, but this is not actually needed. All that is needed is to increment the sub-layer id.

Locate the netebpfext user-mode WFP mock and trace how FWPM_SUBLAYER state is stored and how sub-layer IDs are assigned. Check the existing mock tests or callers before changing the behavior. Done means sub-layer creation increments the ID without tracking unnecessary state and the relevant tests still pass.

Written by the indexing model from the issue text.