[gardening] many_isolates_blocked_at_sleep_test flaky timeouts

[dcharkes]

The tests

vm/dart/isolates/many_isolates_blocked_at_sleep_test Timeout (expected Pass)

are failing on configurations

vm-linux-debug-ia32

flaky -> timeout

It's flaky on a bunch of configurations: https://dart-current-results.web.app/#/filter=vm/dart/isolates/many_isolates_blocked_at_sleep_test&showAll

Possibly related:

• Failures on [vm] If waiting for an active mutator slot for too long, steal a slot from a thread at a native safepoint. #60098

cc @rmacnak-google

[sstrickl]

Seeing additional failures in this and many_isolates_blocked_at_monitor_test today:

The tests

vm/dart/isolates/many_isolates_blocked_at_monitor_test Timeout (expected Pass)
vm/dart/isolates/many_isolates_blocked_at_monitor_test Crash (expected Pass)
vm/dart/isolates/many_isolates_blocked_at_sleep_test Timeout (expected Pass)

are failing on configurations

vm-linux-release-ia32
vm-reload-linux-debug-x64
vm-reload-linux-release-x64
vm-reload-rollback-linux-debug-x64
vm-reload-rollback-linux-release-x64
vm-win-linux-release-ia32

The appropriate portion of the log for the crash on vm-reload-linux-debug-x64:

stderr:
../../runtime/vm/isolate_reload.cc: 2446: error: Type check failed during identity hot reload.
  field: Field <::.mutex>: static late shared
  type: Type: Mutex
  value: _List len:0

version=3.8.0-edge (main) (Unknown timestamp) on "linux_x64"
pid=105806, thread=105929, isolate_group=main(0x561e148e6a00), isolate=(nil)((nil))
os=linux, arch=x64, comp=no, sim=no
isolate_instructions=561e121766e0, vm_instructions=561e121766e0
fp=7fbcc74fc410, sp=7fbcc74fc2e0, pc=561e128532ec
  pc 0x0000561e128532ec fp 0x00007fbcc74fc410 dart::Profiler::DumpStackTrace+0x7c
  pc 0x0000561e121768d4 fp 0x00007fbcc74fc4f0 dart::Assert::Fail+0x84
  pc 0x0000561e126f5508 fp 0x00007fbcc74fc580 dart::FieldInvalidator::CheckStatics+0x6c8
  pc 0x0000561e126d6fa9 fp 0x00007fbcc74fc5f0 dart::IsolateGroup::ForEachIsolate+0xb9
  pc 0x0000561e126f29f7 fp 0x00007fbcc74fc6a0 dart::FieldInvalidator::CheckStatics+0x137
  pc 0x0000561e126f16f8 fp 0x00007fbcc74fcf50 dart::ProgramReloadContext::RunInvalidationVisitors+0x408
  pc 0x0000561e126f0efc fp 0x00007fbcc74fcfc0 dart::ProgramReloadContext::InvalidateWorld+0x9c
  pc 0x0000561e126ebca6 fp 0x00007fbcc74fd030 dart::ProgramReloadContext::ReloadPhase4CommitFinish+0x56
  pc 0x0000561e126e9332 fp 0x00007fbcc74fd2c0 dart::IsolateGroupReloadContext::Reload+0xfc2
  pc 0x0000561e126ddae1 fp 0x00007fbcc74fd370 dart::IsolateGroup::ReloadSources+0x231
...

--- Re-run this test:
python3 tools/test.py -n vm-reload-linux-debug-x64 vm/dart/isolates/many_isolates_blocked_at_monitor_test

[rmacnak-google]

The reload ones have a known cause: #60098