tests: bgp_flowspec expand timings

tests: bgp_flowspec expand timings

Attempt to set the hold time in the bgp flowspec exabgp
config.  In addition it was noticed that upstream bgp_flowspec
tests are still not negotiating peering within the time frame
specified.  This is because the first tcp packet is missed
and no keepalive/hold time are negotiated and exabgp will
not attempt a reconnect for quite some time.  Make this
test slower when things go south.

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