Revert "Allow libz to have stub even though it's not an LLNDK li..."

Revert submission 1312595-zlib_as_stub

Exempt-From-Owner-Approval: reverting a bad change

Reason for revert: broke rvc-dev-plus-aosp
Reverted Changes:
I7c0a7f954:libz is a stub
If51a7e80f:libz provides stubs to Mainline modules.
I26417bb78:Allow libz to have stub even though it's not an LL...

Change-Id: I617eb90a33eacc7f264551c969ff5a16fa0d4087