feat(jobspec): Avoid tests affected by CSIT-1830

feat(jobspec): Avoid tests affected by CSIT-1830

+ Replace TCP TPUT 100b tests on xxv710 NICs with 1518b ones.
 + Keep UDP TPUT tests at 100b for now.
+ Add both 100b and 1518b TCP TPUT tests to Denverton.
 + Its x553 NIC is not affected.
 + That gives us some comparison on how packet size affects performance.

Ticket: CSIT-1830

Change-Id: I5544f7ba84d4813148bcad2f9d64634939492647
Signed-off-by: Vratko Polak <vrpolak@cisco.com>