[FAIL] System.Threading.Tests.PeriodicTimerTests.PeriodicTimer_ActiveOperations_TimerRooted

[AaronRobinsonMSFT]

Failed in https://dev.azure.com/dnceng/public/_build/results?buildId=1669234&view=logs&jobId=f548a91c-a21f-5623-910f-cb06b6e12a1f&j=f548a91c-a21f-5623-910f-cb06b6e12a1f&t=753c1ef2-0d87-52f3-c702-c998a3311d6e

    System.Threading.Tests.PeriodicTimerTests.PeriodicTimer_ActiveOperations_TimerRooted [FAIL]
      Assert.Equal() Failure
      Expected: False
      Actual:   True
      Stack Trace:
        /_/src/libraries/System.Runtime/tests/System/Threading/PeriodicTimerTests.cs(202,0): at System.Threading.Tests.PeriodicTimerTests.WaitForTimerToBeCollected(WeakReference`1 timer, Boolean expected)
        /_/src/libraries/System.Runtime/tests/System/Threading/PeriodicTimerTests.cs(117,0): at System.Threading.Tests.PeriodicTimerTests.PeriodicTimer_ActiveOperations_TimerRooted()
        --- End of stack trace from previous location ---
    System.Tests.StringTests.IndexOf_SingleLetter(s: "Hello", target: '\0', startIndex: 0, count: 5, expected: -1) [SKIP]
      Target \0 is not supported in ICU

[ghost]

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Issue Details

---

Failed in https://dev.azure.com/dnceng/public/_build/results?buildId=1669234&view=logs&jobId=f548a91c-a21f-5623-910f-cb06b6e12a1f&j=f548a91c-a21f-5623-910f-cb06b6e12a1f&t=753c1ef2-0d87-52f3-c702-c998a3311d6e

    System.Threading.Tests.PeriodicTimerTests.PeriodicTimer_ActiveOperations_TimerRooted [FAIL]
      Assert.Equal() Failure
      Expected: False
      Actual:   True
      Stack Trace:
        /_/src/libraries/System.Runtime/tests/System/Threading/PeriodicTimerTests.cs(202,0): at System.Threading.Tests.PeriodicTimerTests.WaitForTimerToBeCollected(WeakReference`1 timer, Boolean expected)
        /_/src/libraries/System.Runtime/tests/System/Threading/PeriodicTimerTests.cs(117,0): at System.Threading.Tests.PeriodicTimerTests.PeriodicTimer_ActiveOperations_TimerRooted()
        --- End of stack trace from previous location ---
    System.Tests.StringTests.IndexOf_SingleLetter(s: "Hello", target: '\0', startIndex: 0, count: 5, expected: -1) [SKIP]
      Target \0 is not supported in ICU

Author:	AaronRobinsonMSFT
Assignees:	-
Labels:	arch-arm32, area-System.Threading, os-linux, untriaged
Milestone:	-

[vcsjones]

I think this one can be duplicated under #59542.