MB-12967 Add additional Unicode collation test

The additional test is purely to prevent future regression the test
currently passes fine on Erlang >= 17.

Change-Id: I85b45be6bf5f4bac3c90620b9fa9d4b62094579e
Reviewed-on: http://review.couchbase.org/44472
Reviewed-by: Volker Mische <volker.mische@gmail.com>
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Harsha H S <hhs.couchbase@gmail.com>