-   The deadlock seems to occur if flag initialization happens to occur while a sample is being created.
    -   Each sample has its own mutex that is locked when a new sample is registered, i.e. created for the first time.
    -   The flag implicitly creates a global sampler object which locks `graveyard_`'s mutex.
-   Usually, in `PushDead`, the `graveyard` is locked before the sample, hence triggering deadlock detection.
-   This lock order can never be recreated since this code is executed exactly once per sample object, and the sample object cannot be accessed until after the method returns.
-   It should therefore be safe to ignore any locking order condition that may occur during sample creation.

PiperOrigin-RevId: 493901903
Change-Id: I094abca82c1a8a82ac392383c72469d68eef09c4