MB-11281: Revert⁴ ".... pass swt low to child erlang"

This reverts commit 295673fbc2b8d399aa67ebad3b5e183534d31e0e.

It looks like swt low works and we're safe to enable it for 3.0 and
beyond.

Change-Id: Id26454e6feb2d80af13dc02b2e315eeaaaf17bb1
Reviewed-on: http://review.couchbase.org/37736
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>