Use SocketKey in MdnsServiceCache am: 775840e1b4

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/2648319

Change-Id: I325cb88b26676e9b6d1921e650780541001b6dd5
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>