tests: Make some tests more robust.

tests: Make some tests more robust.

These tests break if OVS internal hash function is changed.  Some of
this is due to dependency on the order in which elements are iterated
from hash maps, or the algorithm used is just dependent on the
specific hash values produced for specific inputs (groups).  These
changes make these test cases more robust, so that they will not break
so easily due to OVS internal hash function implementation changes.

Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>