Redundant SG rule create calls in unit tests

This patch removes the redundant calls in the test cases.

Closes-Bug: #1302091
Change-Id: I509843b427dc454c0e6b2fd2cbff1bbbb284337f
(cherry picked from commit c49ec8b3ba10bb414a0f135d29ff3685e26d58b3)
Return 409 for second firewall creation

Second firewall creation returns 500, but it is an expected behavior
of firewall reference implementation and an internal server error
should not be returned.

Change-Id: I9f537b238007d35172e2504591d9d3568ba3a41a
Closes-Bug: #1301105
(cherry picked from commit 9df867c672bfb3f80511086c889b744113c56604)
Merge "Redundant SG rule create calls in unit tests" into milestone-proposed
Merge "Return 409 for second firewall creation" into milestone-proposed