pc99: SCHED0011 sometimes times out

[lsf37]

In this run: https://github.com/seL4/util_libs/actions/runs/4920068732/jobs/8789972531?pr=156#step:4:3957 we're getting:

Tue, 09 May 2023 02:21:49 GMT  Test SCHED0010 passed
Tue, 09 May 2023 02:21:49 GMT  </testcase>
Tue, 09 May 2023 02:21:49 GMT  <testcase classname="sel4test" name="SCHED0011">
Tue, 09 May 2023 02:21:49 GMT  Running test SCHED0011 (Test scheduler accuracy)
Tue, 09 May 2023 02:36:11 GMT
Tue, 09 May 2023 02:36:11 GMT  [[Timeout]]
Tue, 09 May 2023 02:36:11 GMT  None
Tue, 09 May 2023 02:36:12 GMT  
Tue, 09 May 2023 02:36:12 GMT  console_run returned -1
Tue, 09 May 2023 02:36:12 GMT  Shutting down haswell4

Note the 15min passing between start of SCHED011 and the timeout.

The failing config was PC99_debug_MCS_clang_32

[wom-bat]

Seem,s to happen randomly. Today https://github.com/seL4/seL4/actions/runs/12040941622/job/33573351124#step:4:23728 on the gcc 32-bit build

[Indanz]

It's x86, you can get an NMI at any time which will take unknown amount of time to be handled by the system firmware. Still, 2 ms deviation seems like a lot.

SCHED0007 and SCHED0008 don't seem to clean up all spawned threads, not sure what effect that has on further tests.