RTT deadline can cause run time-outs

[mfeit-internet2]

Observed that rtt isn't calculating the deadline into the run duration:

pscheduler task rtt --dest 10.0.0.1 --deadline PT20S
Submitting task...
Task URL:
https://tester/pscheduler/tasks/5cc43c85-bfd9-4327-b7a7-c81c0e062533
Running with tool 'ping'
Fetching first run...

Next scheduled run:
https://tester/pscheduler/tasks/5cc43c85-bfd9-4327-b7a7-c81c0e062533/runs/33ce0eed-e474-4a39-97d1-4c707c3dc261
Starts 2024-03-20T20:06:00+00:00 (~2 seconds)
Ends   2024-03-20T20:06:11+00:00 (~10 seconds)
Waiting for result...

Run failed.

Limit system diagnostics for this run:
  No limits were applied

Error from tester:
  Process took too long to run.

Diagnostics from tester:
  ping -n -c 5 -i 1.0 -w 20.0 -W 1.0 10.0.0.1

[mfeit-internet2]

Release Notes:

The ping tool plugin has been modified to handle deadlines properly and to make better use of the tool's output.