tests: Do not do a initial_timeout of 2 seconds for verify_bgp_rib

tests: Do not do a initial_timeout of 2 seconds for verify_bgp_rib

A bunch of tests have this pattern:

a) Install a new prefix into bgp
b) Run this loop:
foreach (router in topology) {
	verify_bgp_rib(router)
}

This is to ensure that the prefix is actually disseminated.
The problem with this, of course, is that a wait of 2 seconds
for every item in that loop makes no sense.  As that the initial
router verification of it's bgp rib will wait 2 seconds and
all the remaining bgp routers in the topology will have gotten
the data.  So we end up waiting a bunch of extra time.

Remove the initial_wait time for verify_bgp_rib.  Also
increase the failure wait time to 30 seconds.  This is
to give a bigger window for bgp to send it's data for
our test systems that could be under heavy load.  In the
normal case tests will never hit this.

Signed-off-by: Donald Sharp <sharpd@nvidia.com>