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
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:f3f48883bcfe8a8f46fdec7affd545c81ba1a8ee)
Merged-In: I00a9840a69d06c6f4246a2db284c3060392b302b
Change-Id: I00a9840a69d06c6f4246a2db284c3060392b302b