Optimize mDNS packet chunk preloading for RAM efficiency

This commit optimizes the preloading of mDNS v4 and v6 packet chunks
into the data region, preventing duplicate storage of MAC and IPv6
addresses. This optimization reduces the generated program size from
4342 to 4289 bytes, saving 53 bytes of RAM.

Test: TH
Change-Id: Ia633a68ffa97d4294381f533d76821055f91aa04