Make leafrefFromLeafListToLeafTest impervious to list order

Make leafrefFromLeafListToLeafTest impervious to list order

In NnToJsonLeafrefType#leafrefFromLeafListToLeafTest, the leaf list is
unordered but the regex expects a certain order based on the way the
list is currently hashed. But this makes it susceptible to failure if
something changes upstream to alter the order. So I changed the regex to
not depend on the order.

Note: an upcoming yang tools patch will alter the order as a side effect
that affects this test.

Change-Id: Ibf95271b008134c3f75fc99c9ee7ba0d643dfe7a
Signed-off-by: Tom Pantelis <tpanteli@brocade.com>