chore(llmobs): add span.finished telemetry metric

[Yun-Kim]

What does this PR do?

Adds the span.finished telemetry count metric to LLMObs spans before submitting to Datadog, in the LLMObsSpanProcessor.process() method. Also adds a minor _ml_obs.integration internal span store key-value pair to keep track of which integration a span originates from.

Todo: add _ml_obs.decorator internal span store key-value pair to keep track whether a span is created from a decorator.

Motivation

Plugin Checklist

• Unit tests.
• TypeScript definitions.
• TypeScript tests.
• API documentation.
• CircleCI jobs/workflows.
• Plugin is exported.

Additional Notes

[github-actions]

Overall package size

Self size: 9 MB
Deduped: 101.53 MB
No deduping: 102.04 MB

Dependency sizes

| name | version | self size | total size | |------|---------|-----------|------------| | @datadog/libdatadog | 0.5.0 | 29.83 MB | 29.83 MB | | @datadog/native-appsec | 8.5.1 | 19.26 MB | 19.27 MB | | @datadog/native-iast-taint-tracking | 3.3.0 | 13.77 MB | 13.78 MB | | @datadog/pprof | 5.6.0 | 9.79 MB | 10.16 MB | | @opentelemetry/core | 1.30.1 | 908.66 kB | 7.16 MB | | protobufjs | 7.4.0 | 2.77 MB | 5.42 MB | | @datadog/native-iast-rewriter | 2.8.0 | 2.6 MB | 2.74 MB | | @datadog/native-metrics | 3.1.0 | 1.06 MB | 1.46 MB | | @opentelemetry/api | 1.8.0 | 1.21 MB | 1.21 MB | | import-in-the-middle | 1.13.1 | 117.64 kB | 839.26 kB | | source-map | 0.7.4 | 226 kB | 226 kB | | opentracing | 0.14.7 | 194.81 kB | 194.81 kB | | lru-cache | 7.18.3 | 133.92 kB | 133.92 kB | | pprof-format | 2.1.0 | 111.69 kB | 111.69 kB | | @datadog/sketches-js | 2.1.1 | 109.9 kB | 109.9 kB | | lodash.sortby | 4.7.0 | 75.76 kB | 75.76 kB | | ignore | 5.3.2 | 53.63 kB | 53.63 kB | | istanbul-lib-coverage | 3.2.0 | 29.34 kB | 29.34 kB | | rfdc | 1.4.1 | 27.15 kB | 27.15 kB | | @isaacs/ttlcache | 1.4.1 | 25.2 kB | 25.2 kB | | tlhunter-sorted-set | 0.1.0 | 24.94 kB | 24.94 kB | | dc-polyfill | 0.1.6 | 24.56 kB | 24.56 kB | | shell-quote | 1.8.2 | 23.54 kB | 23.54 kB | | limiter | 1.1.5 | 23.17 kB | 23.17 kB | | retry | 0.13.1 | 18.85 kB | 18.85 kB | | semifies | 1.0.0 | 15.84 kB | 15.84 kB | | jest-docblock | 29.7.0 | 8.99 kB | 12.76 kB | | crypto-randomuuid | 1.0.0 | 11.18 kB | 11.18 kB | | ttl-set | 1.0.0 | 4.61 kB | 9.69 kB | | path-to-regexp | 0.1.12 | 6.6 kB | 6.6 kB | | koalas | 1.0.2 | 6.47 kB | 6.47 kB | | module-details-from-path | 1.0.3 | 4.47 kB | 4.47 kB |

_{🤖 This report was automatically generated by heaviest-objects-in-the-universe}

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 57.10%. Comparing base (5e794c7) to head (c5db57b).
Report is 2 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #5444       +/-   ##
===========================================
- Coverage   79.57%   57.10%   -22.47%     
===========================================
  Files         510       37      -473     
  Lines       22898     1527    -21371     
===========================================
- Hits        18220      872    -17348     
+ Misses       4678      655     -4023     

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[datadog-datadog-prod-us1]

Datadog Report

Branch report: yunkim/llmobs-telemetry
Commit report: ba99a47
Test service: dd-trace-js-integration-tests

✅ 0 Failed, 802 Passed, 0 Skipped, 9m 2.77s Total Time

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-03-19 21:36:21

Comparing candidate commit c5db57b in PR branch yunkim/llmobs-telemetry with baseline commit 5e794c7 in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 918 metrics, 15 unstable metrics.