Use PerfParalellResult and `asyncio.subprocess` for TrafficControl results

[pgagne]

Description

Changing to perf paralell result. mostly complete. commiting for test and review purposes.

Also use asyncio.subprocess to run multiple tc instances client side.

For reference here is a sample of the tc process start timestamps:

    data:
        instance_results:
            item 0:
                ...
                start_timestamp: 1681069428.9487906
                ...
            item 1:
                ...
                start_timestamp: 1681069428.9511075
                ... 
            item 2:
                ...
                start_timestamp: 1681069428.9530337
                ...
            item 3:
                ...
                start_timestamp: 1681069428.9548721
                ...

[pgagne]

@olichtne @jtluka

Please review, this should be ready to go. Let me know if you have any questions.

Test jobs:

J:7716681 J:7713522 J:7720505

[olichtne]

Test jobs:

J:7716681 J:7713522 J:7720505

none of these jobs actually test the parallel functionality, i assume you also have a job for that somewhere?

ah nevermind... you just don't print it in the result descriptions. ignore this comment.

[pgagne]

@olichtne fixed issues. Also I added the number of instances to the result description to make it clearer how many instances there are.