`DelayedActionRendererTest.ClearRenderBufferWhenItsInterval()` is flaky

[dahlia]

https://app.circleci.com/pipelines/github/planetarium/libplanet/2422/workflows/4a7a6864-8d18-4812-8e92-0b2744cc3ac0/jobs/14794

Assert.Equal() Failure
Expected: 17
Actual:   14
  at Libplanet.Tests.Blockchain.Renderers.DelayedActionRendererTest+<ClearRenderBufferWhenItsInterval>d__6.MoveNext () [0x004b6] in /mnt/ramdisk/Libplanet.Tests/Blockchain/Renderers/DelayedActionRendererTest.cs:500 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000c] in <a1e9f114a6e64f4eacb529fc802ec93d>:0 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x0003e] in <a1e9f114a6e64f4eacb529fc802ec93d>:0 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x00028] in <a1e9f114a6e64f4eacb529fc802ec93d>:0 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x00008] in <a1e9f114a6e64f4eacb529fc802ec93d>:0 
  at System.Runtime.CompilerServices.TaskAwaiter.GetResult () [0x00000] in <a1e9f114a6e64f4eacb529fc802ec93d>:0 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000c] in <a1e9f114a6e64f4eacb529fc802ec93d>:0 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x0003e] in <a1e9f114a6e64f4eacb529fc802ec93d>:0 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x00028] in <a1e9f114a6e64f4eacb529fc802ec93d>:0 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x00008] in <a1e9f114a6e64f4eacb529fc802ec93d>:0 
  at System.Runtime.CompilerServices.TaskAwaiter.GetResult () [0x00000] in <a1e9f114a6e64f4eacb529fc802ec93d>:0 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000c] in <a1e9f114a6e64f4eacb529fc802ec93d>:0 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x0003e] in <a1e9f114a6e64f4eacb529fc802ec93d>:0 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x00028] in <a1e9f114a6e64f4eacb529fc802ec93d>:0 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x00008] in <a1e9f114a6e64f4eacb529fc802ec93d>:0 
  at System.Runtime.CompilerServices.TaskAwaiter.GetResult () [0x00000] in <a1e9f114a6e64f4eacb529fc802ec93d>:0 

[tkiapril]

The actual value itself is flaky, I've seen it return 11 sometimes.

[dahlia]

I thought it fails with only Unity Mono, but it turns out that it fails on .NET Core as well.