KAFKA-21016: Add client quota-utilization metrics (KIP-1373)

[manangupta111]

Summary

• Adds quota-utilization on the existing Produce, Fetch, and Request quota MBeans (no new sensor, ObjectName, or quota entity).
• Value is measured-rate / effective-quota * 100 using the cached MetricConfig bound used for enforcement. It is not capped at 100; unlimited, missing, and non-positive bounds return NaN.
• ControllerMutation is excluded (token-bucket enforcement does not match this rate-utilization definition).
• Measurement does not call ClientQuotaCallback.quotaLimit().

Test plan

• Unit tests
• jmx metrics

$>domain kafka.server
#domain is set to kafka.server
$>bean kafka.server:type=Produce,client-id=mg-quota-load-test-client
#bean is set to kafka.server:type=Produce,client-id=mg-quota-load-test-client
$>info
#mbean = kafka.server:type=Produce,client-id=mg-quota-load-test-client
#class name = org.apache.kafka.common.metrics.JmxReporter$KafkaMbean
# attributes
  %0   - byte-rate (double, r)
  %1   - quota-utilization (double, r)
  %2   - throttle-time (double, r)
#there's no operations
#there's no notifications
$>get quota-utilization
#mbean = kafka.server:type=Produce,client-id=mg-quota-load-test-client:
quota-utilization = 21.582440162437226;

KIP-1373: Client Quota Utilization Metrics