Fetch the query quota capacity utilization rate broker metric in a callback function

[jackjlli]

This PR fetches the query quota capacity utilization rate broker metric in a callback function. Related issue: https://github.com/apache/pinot/issues/12768

The reason is that this broker metric is a gauge metric. If there is no incoming query, the gauge value would remain the same without any updates. In addition, if the total query quota is less than the number of brokers, meaning if the per-broker rate is less than 1, the metric value would always be > 100. So even there is only 1 incoming query for a while, the metric value would still be > 100.

[Jackie-Jiang]

@zhtaoxiang Can you help take a look?