Use coarse time when calculating metrics refresh interval

[andygrove]

What is the problem the feature request solves?

See comment at #1329 (comment)

Describe the potential solution

No response

Additional context

No response

[andygrove]

Closing this, since the loop it was about is gone. The interval check's Instant::now() used to run on every spin of the busy-poll loop in executePlan. #2940 cut that to once per 100 polls, and #6219 replaced the busy loop with one that parks while it waits on native I/O. What's left is one clock read per output batch and one per pending poll. Each of those sits next to a JNI handoff, a pull from the JVM or a wake-up that costs far more than the read. Most DataFusion operators also read the clock twice per batch for their own metrics, and coarsetime can't reach those, so switching this one call would add a dependency without a measurable gain. Happy to reopen if a profile says otherwise.