Support additional labels for PodMonitor to be discovered by Prometheus

[eric9204]

Why are the changes needed?

the prometheus can not discover the podMonitor created by kyuubi helm chart.

How was this patch tested?

1. enable pod monitor:

metrics:
  # Enable metrics system, used for 'kyuubi.metrics.enabled' property
  enabled: true
  # A comma-separated list of metrics reporters, used for 'kyuubi.metrics.reporters' property
  reporters: PROMETHEUS
  # Prometheus port, used for 'kyuubi.metrics.prometheus.port' property
  prometheusPort: 10019

  # PodMonitor by Prometheus Operator
  podMonitor:
    # Enable PodMonitor creation
    enabled: true
    # List of pod endpoints serving metrics to be scraped by Prometheus, see Prometheus Operator docs for more details
    #podMetricsEndpoints: []
    podMetricsEndpoints:
      - path: /metrics
        port: prometheus

2. Helm install kyuubi .
3. check prometheus web ui.

Was this patch authored or co-authored using generative AI tooling?

No

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 0.00%. Comparing base (99e27d4) to head (f8fa51f).

Additional details and impacted files

@@          Coverage Diff           @@
##           master   #6845   +/-   ##
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  Coverage    0.00%   0.00%           
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  Files         687     687           
  Lines       42463   42463           
  Branches     5796    5796           
======================================
  Misses      42463   42463           

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[pan3793]

thanks, merged to master