Optimize BlockOnLock retry loop to eliminate per-iteration allocations

[Copilot]

Addresses feedback on #10442 to reduce GC churn in the BlockOnLock retry loop. The original implementation allocated a new timer on each iteration via time.After(), causing unnecessary memory pressure when locks are held for extended periods.

Changes

• Added lockRetryInterval constant: Extracts hardcoded 10ms retry interval into a named constant for clarity and tunability
• Replaced time.After with lazy-initialized time.Ticker: Single ticker instance reused across all retries, eliminated per-iteration allocations
• Optimized fast path: Ticker creation deferred until first lock failure, avoiding overhead when lock is immediately available

Before

for {
    err = lock.TryLock()
    if err == nil {
        break
    }
    select {
    case <-ctx.Done():
        return nil, ctx.Err()
    case <-time.After(10 * time.Millisecond):  // New allocation each iteration
    }
}

After

var ticker *time.Ticker
defer func() {
    if ticker != nil {
        ticker.Stop()
    }
}()
for {
    err = lock.TryLock()
    if err == nil {
        break
    }
    if ticker == nil {
        ticker = time.NewTicker(lockRetryInterval)  // Allocate once, reuse
    }
    select {
    case <-ctx.Done():
        return nil, ctx.Err()
    case <-ticker.C:
    }
}

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