kernel mode stress test - tweak extension stop/restart, better handling of test runtime

[dv-msft]

Description

This PR adds some runtime tweaks to fix some non-test-related but intrusive issues. Specifically:

1. Ignore 'advisory' return status codes from OS/runtime APIs to start/stop NetEbpfExt (i.e., 'driver already stopping/stopped'/'driver start-pending/already started'). These were treated as 'fatal' errors leading to false positives.
2. Plumb test runtime awareness deeper into long running functions to ensure as timely test termination as possible. Currently, in some cases the actual runtime far exceeded the specified runtime.
3. Separate out test cases for 'JIT' and 'native' ebpf programs into respective 'test classes'. This now allows us to run 'JIT-only' or 'native-only' tests if required. (Default is still 'all').

Testing

This is test collateral.

Documentation

No documentation changes required.

Fixes #2520

[codecov]

Codecov Report

Merging #2519 (f52c41f) into main (396412b) will decrease coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #2519      +/-   ##
==========================================
- Coverage   84.12%   84.08%   -0.04%     
==========================================
  Files         157      157              
  Lines       28978    28978              
==========================================
- Hits        24377    24366      -11     
- Misses       4601     4612      +11     

see 5 files with indirect coverage changes