Use non-next NetworkStack

NetworkStack now builds against stable T APIs, so T 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.

This change should not go into development branches using unstable SDKs
(including aosp/master downstreams), as per the merged-in.

Bug: 216396304
Test: m
Merged-In: I12348bd913f724c4675177ce6cdf582948d9d03c
Change-Id: I8788c5af37c862e9a74cc140d1dc917fb15ec5a9