feat(sdk-node): wire up metric producers from declarative config

[MikeGoldsmith]

Which problem is this PR solving?

The declarative config schema supports producers on periodic metric readers (currently only opencensus), but getMeterReadersFromConfiguration ignores them — producers are never passed to PeriodicExportingMetricReader.

Short description of the changes

• Add getMetricProducersFromConfiguration that resolves config model producers to SDK MetricProducer instances
• For opencensus: dynamically require('@opentelemetry/shim-opencensus') to avoid a hard dependency — users who configure opencensus producers must install the shim package separately
• Warn if the shim package is not installed, or if an unknown producer type is configured
• Pass resolved metricProducers to PeriodicExportingMetricReader for both OTLP and console exporters

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

189 sdk-node tests pass. Full lint passes.

Checklist:

• Followed the style guidelines of this project
• Unit tests have been added
• Documentation has been updated

Closes #6424

[codecov]

Codecov Report

❌ Patch coverage is 92.85714% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 94.85%. Comparing base (c390f54) to head (9f88a33).
⚠️ Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
...ental/packages/opentelemetry-sdk-node/src/utils.ts	92.85%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6712      +/-   ##
==========================================
- Coverage   94.86%   94.85%   -0.02%     
==========================================
  Files         376      377       +1     
  Lines       12717    12765      +48     
  Branches     2884     2891       +7     
==========================================
+ Hits        12064    12108      +44     
- Misses        653      657       +4     

Files with missing lines	Coverage Δ
...ental/packages/opentelemetry-sdk-node/src/utils.ts	97.08% <92.85%> (-0.12%)	⬇️

... and 5 files with indirect coverage changes

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[trentm]

Just a nit. Not merging yet, to give Mike a chance to address the nit.

[trentm]

@MikeGoldsmith I broke test/start.test.ts in a mismerge (using the GitHub UI to resolve a conflict).
Here is a fix:

diff --git a/experimental/packages/opentelemetry-sdk-node/test/start.test.ts b/experimental/packages/opentelemetry-sdk-node/test/start.test.ts
index ede4ccd37..8f6021b06 100644
--- a/experimental/packages/opentelemetry-sdk-node/test/start.test.ts
+++ b/experimental/packages/opentelemetry-sdk-node/test/start.test.ts
@@ -986,6 +986,8 @@ describe('startNodeSDK', function () {
         )
       );
       await (reader as PeriodicExportingMetricReader).shutdown();
+    });
+
     it('should warn when exporter timeout is 0', async () => {
       const warnSpy = Sinon.spy(diag, 'warn');
       const exporter = getSpanExporter({

Can you please apply this?
I'm unable to push to your branch:

% git push honeycombio mike/set-meter-producer
ERROR: Permission to honeycombio/opentelemetry-js.git denied to trentm.
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

which I think is (always/often?) the case with corporate forks.

(Aside: I find it inconsistent that I cannot push to this fork, but if there is a merge conflict, the GitHub UI allows me to push a commit along with any edits I've made to that file.)

[trentm]

See the fix from #6712 (comment) (comment just above) because I mucked up a merge conflict.

[MikeGoldsmith]

Thanks @trentm - I've applied the fix, should be good now.