[Bug] [SpecDecode] Speculative metrics very unlikely to get logged

[tdoublep]

Your current environment

n/a

🐛 Describe the bug

After merging #6578, the AsyncMetricsCollector now respects the time interval between collecting speculative decoding metrics. It now collects the metrics every 5 seconds, instead of continuously collecting them.

While this is the desired behaviour, I now see that in practice, we are never logging the speculative decoding stats. This is because, in order to get logged, the speculative decoding stats need to happen to be collected in exactly the same step that we decide to log the output (which is controlled by a different time interval). In practice, this does not seem to happen using the default settings.