Remove obsolete mDNS offload code for clarity

Removed the existing mDNS offload code, which is no longer relevant for
the upcoming APFv6-based implementation. This cleanup ensures a cleaner
and more focused review process for the new mDNS offload program.

Test: TH
Change-Id: Ibef94b5dd4483ce2d3782746bacc7984999d4404
1 file changed