Refactor RFC2455 TRex traffic profile injection

Refactor RFC2455 TRex traffic profile injection

The TRex RFC2455 traffic profile configures the duration of the traffic
injection. Once the traffic is started, the traffic profile should poll
the traffic injector client for the injection status. When the injection
is finished, the traffic execution should end.

Instead of this, the traffic profile waits a fixed time (using time.sleep
method) and then stops the traffic. This approach is not accurate and may
cause shorter injection periods.

JIRA: YARDSTICK-1197

Change-Id: I5090df81ef4ec7945ff6c1aff070656b48e0fe77
Signed-off-by: Rodolfo Alonso Hernandez <rodolfo.alonso.hernandez@intel.com>