Initialize callbacks in fuzzer am: 857ece4f am: 68de805a am: bcba6bc3 am: a85c2ac7 am: 5be073ac

Original change: https://android-review.googlesource.com/c/platform/packages/modules/DnsResolver/+/2469762



Change-Id: I93baf07d00735d6ea78729a24f2f11f6b5bef9df
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>