Fix crashtracking specs

[lloeki]

What does this PR do?

Reinstate crashtracking specs by fixing them.

Motivation:

• Disable crashtracking by default #3970 identified these specs as being unreliable and/or leaking threads.
• Coverage is both limited and relies on internal behaviours.
• Crashtracking changes to address Crash tracker spawning long-running child processes? #3954 will make these same specs fail.

Additional Notes:

How to test the change?

Well, specs!

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-10-09 15:16:35

Comparing candidate commit 9972962 in PR branch lloeki/fix-crashtracking-specs with baseline commit 8bc0e5e in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 23 metrics, 2 unstable metrics.