examples/opentelemetry: enabling experimental metrics

[vinothkumarr227]

Fixes #8311

RELEASE NOTES: N/A

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.48%. Comparing base (8adcc94) to head (2b67a2b).
⚠️ Report is 6 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8441      +/-   ##
==========================================
+ Coverage   82.31%   82.48%   +0.16%     
==========================================
  Files         414      413       -1     
  Lines       40464    40513      +49     
==========================================
+ Hits        33308    33416     +108     
+ Misses       5791     5744      -47     
+ Partials     1365     1353      -12     

see 27 files with indirect coverage changes

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[eshitachandwani]

Please link the comment in response to which this PR has been raised. @vinothkumarr227

[vinothkumarr227]

@arjan-bal This fix was made following the review comment from in this discussion

[eshitachandwani]

Correct me if I am wrong but I dont think we are using xds in this example , so using xds metrics might not make sense. Can you change to use some other metrics? Example : grpc.lb.pick_first. connection_attempts_succeeded

[vinothkumarr227]

@eshitachandwani , Thanks for the review! I don’t think we need to change this example — we’ve already mentioned that it’s meant to demonstrate experimental metrics. Also, this is aligned with the discussion here: grpc-go#8234 (comment).

[eshitachandwani]

But the example in my opinion should be a working example , like if someone is trying to run the example , they should be able to see some metrics. And since the example is not using xds , there will be no metrics for the xds client.

[vinothkumarr227]

Thanks for the feedback! I’ve updated the example to use pick_first with a valid address, and it now emits metrics

[eshitachandwani]

Adding @arjan-bal for a second review.