Revert² "MB-9480: Revert "MB-9457: pass swt low to child erlang""

This reverts commit 2aa9df23bc2548b52bd549b6598a197686c7a41e.

This is _removal_ of swt low again. We're not sure it's actually
working and plan is to test it as part of 2.5.1 release. And only then
we'll enable it for master. The idea is master has it's own share of
challenges already so 2.5.1 is better "test ground".

Change-Id: I89e8ab3c050dcb5abb35cdb40509b3d521246c70
Reviewed-on: http://review.couchbase.org/33591
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>