Increase min_rate for NDRPDR tests

Increase min_rate for NDRPDR tests

Latency measurements break for loads less than 9 kpps per direction.
Setting min_rate to 90 kpps prevents 10% latency trial from breaking.
90 kpps should be enough for any type of test.

When some test finds a lower value, this patch will make the fail
with a message saying the loss rate at minimal load is too high
(instead of a cryptic error from 10% measurement without this patch).

Change-Id: I97b8428aa5044da23343b86447857b3a101f6baa
Signed-off-by: Vratko Polak <vrpolak@cisco.com>