Add metrics queues custom docs

[bjmcnic]

Change Summary

Add Endpoint.metrics.queue_metric.* to custom docs to fix EAF failures:

AssertionError: Found documents with fields missing custom documentation, count: 2, undocumented keys: {'Endpoint.metrics.queue_metrics.user.async_kernel_event_queue.drops', 'Endpoint.metrics.queue_metrics.user.async_kernel_event_queue.size', 'Endpoint.metrics.queue_metrics.kernel.send_to_user_queue.drops', 'Endpoint.metrics.queue_metrics.kernel.send_to_user_queue.size'}. Documents written to custom_documentation_violations.ndjson

Q/A

For mapping changes:

• I ran make after making the schema changes, and committed all changes

Release Target

8.17.6.