vrrp: unit tests do not run by default

Type: fix
Fixes: 39e9428b90

VRRP unit tests fail sometimes for changes which have not touched any
code related to VRRP. There were some timing-related changes recently
which probably made the VRRP tests, which rely on a VR changing state
within a certain amount of time, start failing.

Set the VRRP tests to only run with the extended tests rather than
running by default. This is temporary so VRRP will not cause spurious
build failures while a proper solution is figured out.

Change-Id: I5826ea39b944dfb9b0ca4bdfa2ebbe86d269f935
Signed-off-by: Matthew Smith <mgsmith@netgate.com>