/data/nativetest[64] processes are running with the new ns config

Native tests under /data/nativetest[64] directory is now running with
the same linker namespace configuration as /system/bin/* processes.

This allows us to stop mimicing the linker namespace configuration of the
/system/bin/* processes using LD_LIBRARY_PATH.

Bug: 63597267
Test: run bionic-unit-tests
Test: run linker-unit-tests
Change-Id: If8e2ed0b8016e4e07bf6829735b8e02f952042d0