test_routers_ha: Unify creating routers

Change Ib12986c25eda25970445169310c7c0334d6da49c introduces a mechanism
that creates a router and stores it later for automatic deletion. This
patch adopts the whole test_routers_ha test suite. Patch also moves
deleting router in check method to clean up router even when ha routers
are supported.

Change-Id: I3ead8b526615b0ff8214ec8994f47409f18ea439
1 file changed