[fix][spm]: Change default metrics namespace to match new default in spanmetricsconnector

[mahadzaryab1]

Which problem is this PR solving?

• Resolves SPM is broken by OTEL's new version #5982

Description of the changes

• Make traces_span_metrics the new namespace default.
• Fixed the failing SPM integration test by setting the default namespace when querying from prometheus to traces_span_metrics. This matches the new default namespace in the spanmetricsconnector which was changed in v0.109.0 (see f7o/opentelemetry-collector-contrib@371bc59)
• This change is backwards compatible because it modifies the default. As a result, if anyone isn't using a custom namespace they will not be broken by these changes.

How was this change tested?

• CI

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 96.79%. Comparing base (ff1b678) to head (cd5c713).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6007      +/-   ##
==========================================
+ Coverage   96.78%   96.79%   +0.01%     
==========================================
  Files         348      348              
  Lines       16559    16559              
==========================================
+ Hits        16027    16029       +2     
+ Misses        343      342       -1     
+ Partials      189      188       -1     

Flag	Coverage Δ
badger_v1	8.02% <ø> (ø)
badger_v2	1.82% <ø> (ø)
cassandra-4.x-v1	16.61% <ø> (ø)
cassandra-4.x-v2	1.75% <ø> (ø)
cassandra-5.x-v1	16.61% <ø> (ø)
cassandra-5.x-v2	1.75% <ø> (ø)
elasticsearch-6.x-v1	18.77% <ø> (-0.02%)	⬇️
elasticsearch-7.x-v1	18.83% <ø> (ø)
elasticsearch-8.x-v1	19.04% <ø> (ø)
elasticsearch-8.x-v2	1.82% <ø> (+0.01%)	⬆️
grpc_v1	9.51% <ø> (-0.02%)	⬇️
grpc_v2	7.15% <ø> (ø)
kafka-v1	9.74% <ø> (ø)
kafka-v2	1.82% <ø> (ø)
memory_v2	1.82% <ø> (ø)
opensearch-1.x-v1	18.88% <ø> (ø)
opensearch-2.x-v1	18.89% <ø> (ø)
opensearch-2.x-v2	1.82% <ø> (ø)
tailsampling-processor	0.46% <ø> (ø)
unittests	95.28% <ø> (+0.01%)	⬆️

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[mahadzaryab1]

@yurishkuro setting this default here seems to take care of the v2 test but the v1 test is still getting an empty response. do you have any idea why that could be? both v1 and v2 read this config.

[mahadzaryab1]

this was actually not related to the changes in this PR and was failing due to missing http receiver endpoint in the otel collector config but wasn't failing before because the version was pinned to 0.89.0

[yurishkuro]

Thanks for digging into this one! 🥳