[fix][ci] Change the prometheus healthcheck endpoint

[mahadzaryab1]

Description of the changes

• The SPM integration test in the CI has been failing consistently. It looks like the default endpoint for prometheus has changed from localhost:9090/graph to localhost:9090/query. This PR fixes that in the integration test and in the README.

How was this change tested?

• Integration test passes
• Ran the docker-compose/monitor/docker-compose-v2.yml example and verified that the prometheus UI displays the metrics at the new endpoint.

Checklist

• I have read https://github.com/jaegertracing/jaeger/blob/master/CONTRIBUTING_GUIDELINES.md
• I have signed all commits
• I have added unit tests for the new functionality
• I have run lint and test steps successfully
  • for jaeger: make lint test
  • for jaeger-ui: yarn lint and yarn test

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.47%. Comparing base (eb6c5c9) to head (9dfa00f).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6217   +/-   ##
=======================================
  Coverage   96.47%   96.47%           
=======================================
  Files         354      354           
  Lines       20127    20127           
=======================================
  Hits        19418    19418           
  Misses        524      524           
  Partials      185      185           

Flag	Coverage Δ
badger_v1	8.31% <ø> (ø)
badger_v2	1.67% <ø> (ø)
cassandra-4.x-v1	14.39% <ø> (ø)
cassandra-4.x-v2	1.61% <ø> (ø)
cassandra-5.x-v1	14.39% <ø> (ø)
cassandra-5.x-v2	1.61% <ø> (ø)
elasticsearch-6.x-v1	18.60% <ø> (ø)
elasticsearch-7.x-v1	18.68% <ø> (ø)
elasticsearch-8.x-v1	18.84% <ø> (-0.01%)	⬇️
elasticsearch-8.x-v2	1.67% <ø> (ø)
grpc_v1	9.47% <ø> (-0.01%)	⬇️
grpc_v2	7.00% <ø> (+<0.01%)	⬆️
kafka-v1	8.88% <ø> (ø)
kafka-v2	1.67% <ø> (ø)
memory_v2	1.67% <ø> (ø)
opensearch-1.x-v1	18.72% <ø> (ø)
opensearch-2.x-v1	18.72% <ø> (-0.01%)	⬇️
opensearch-2.x-v2	1.67% <ø> (ø)
tailsampling-processor	0.46% <ø> (ø)
unittests	95.38% <ø> (ø)

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[yurishkuro]

Thanks!