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

This reverts commit 27f631902d17aec23a007826758bdf7722a7ed13.

It appears that +swt low triggers some erlang VM bug that caused nodes
to hang.

Change-Id: I8ccbbeff42e3adcc4e0943bc0c8bcb5c07c468bb
Reviewed-on: http://review.couchbase.org/30328
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Artem Stemkovski <artem@couchbase.com>