Freeze netd AIDL interface

This freezes the interface as of the latest beta build, although it has
not changed since then.

Generated with:
m netd_aidl_interface-freeze-api

Test: flashed, WiFi working
Test: atest netd_unit_test netd_integration_test netdutils_test
Bug: 128803828

Merged-In: I34a282393396e8bb2f6a3c2a0a5726f90e996cf2
Merged-In: Ia2cc2413cf1f19ca4e75e915b460cf6133c77a55
(cherry picked from commit dbf21999)

Change-Id: Ibd01bce7a7e0becda1569743d3684e2278ad6f36