Use non-next NetworkStack

NetworkStack now builds against stable U APIs, so U can use
the stable binaries instead of the "next" versions.

Since it has just been bumped, NetworkStack is equivalent to
NetworkStackNext at this point, so this is a no-op.

Bug: 280250560
Test: m
Ignore-AOSP-First: This CL will be cherry-picked to aosp
Change-Id: I00a9840a69d06c6f4246a2db284c3060392b302b