Fix dead code: !completedTask.IsCompleted always false in hedge timer loop

[Copilot]

Task.WhenAny always returns a task already in a terminal state, so completedTask.IsCompleted is invariably true — making !completedTask.IsCompleted dead code that never triggered. The intended behavior (skip spawning new hedge requests when the timer ended abnormally) was silently broken.

Change

• Replaced !completedTask.IsCompleted with completedTask.IsFaulted || completedTask.IsCanceled to correctly detect abnormal timer completion (cancelled via linked CTS on e2e timeout, or faulted)
• IsCompletedSuccessfully was not used — unavailable on netstandard2.0

// Before — !IsCompleted is always false; condition reduced to just IsCancellationRequested
while (
    completedTask == hedgeTimer &&
    (!completedTask.IsCompleted || applicationProvidedCancellationToken.IsCancellationRequested));

// After — correctly detects cancelled/faulted timer
while (
    completedTask == hedgeTimer &&
    (completedTask.IsFaulted || completedTask.IsCanceled || applicationProvidedCancellationToken.IsCancellationRequested));

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