chore(telemetry): improves typing for telemetry metric namespaces

[mabdinur]

Follow up to: #11565

Prevents telemetry metrics from being queued with an invalid namespace

Checklist

• PR author has checked that all the criteria below are met
• The PR description includes an overview of the change
• The PR description articulates the motivation for the change
• The change includes tests OR the PR description describes a testing strategy
• The PR description notes risks associated with the change, if any
• Newly-added code is easy to change
• The change follows the library release note guidelines
• The change includes or references documentation updates if necessary
• Backport labels are set (if applicable)

Reviewer Checklist

• Reviewer has checked that all the criteria below are met
• Title is accurate
• All changes are related to the pull request's stated goal
• Avoids breaking API changes
• Testing strategy adequately addresses listed risks
• Newly-added code is easy to change
• Release note makes sense to a user of the library
• If necessary, author has acknowledged and discussed the performance implications of this PR as reported in the benchmarks PR comment
• Backport labels are set in a manner that is consistent with the release branch maintenance policy

[github-actions]

CODEOWNERS have been resolved as:

ddtrace/_monkey.py                                                      @DataDog/apm-core-python
ddtrace/_trace/processor/__init__.py                                    @DataDog/apm-sdk-api-python
ddtrace/_trace/telemetry.py                                             @DataDog/apm-sdk-api-python
ddtrace/appsec/_iast/_metrics.py                                        @DataDog/asm-python
ddtrace/appsec/_metrics.py                                              @DataDog/asm-python
ddtrace/internal/ci_visibility/telemetry/api_request.py                 @DataDog/ci-app-libraries
ddtrace/internal/ci_visibility/telemetry/constants.py                   @DataDog/ci-app-libraries
ddtrace/internal/ci_visibility/telemetry/coverage.py                    @DataDog/ci-app-libraries
ddtrace/internal/ci_visibility/telemetry/early_flake_detection.py       @DataDog/ci-app-libraries
ddtrace/internal/ci_visibility/telemetry/events.py                      @DataDog/ci-app-libraries
ddtrace/internal/ci_visibility/telemetry/git.py                         @DataDog/ci-app-libraries
ddtrace/internal/ci_visibility/telemetry/itr.py                         @DataDog/ci-app-libraries
ddtrace/internal/ci_visibility/telemetry/payload.py                     @DataDog/ci-app-libraries
ddtrace/internal/telemetry/constants.py                                 @DataDog/apm-core-python
ddtrace/internal/telemetry/metrics_namespaces.py                        @DataDog/apm-core-python
ddtrace/internal/telemetry/writer.py                                    @DataDog/apm-core-python
ddtrace/llmobs/_evaluators/ragas/faithfulness.py                        @DataDog/ml-observability
ddtrace/llmobs/_evaluators/runner.py                                    @DataDog/ml-observability
ddtrace/llmobs/_evaluators/sampler.py                                   @DataDog/ml-observability
ddtrace/settings/_otel_remapper.py                                      @DataDog/apm-core-python
tests/appsec/appsec/test_telemetry.py                                   @DataDog/asm-python
tests/appsec/contrib_appsec/utils.py                                    @DataDog/asm-python
tests/appsec/iast/test_telemetry.py                                     @DataDog/asm-python
tests/telemetry/app.py                                                  @DataDog/apm-python
tests/telemetry/test_telemetry_metrics.py                               @DataDog/apm-python
tests/tracer/test_processors.py                                         @DataDog/apm-sdk-api-python

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-12-20 19:50:00

Comparing candidate commit c6a9f2f in PR branch munir/fix-type-checking-for-telemetry-namespace with baseline commit 6ea56c5 in branch main.

Found 0 performance improvements and 2 performance regressions! Performance is the same for 392 metrics, 2 unstable metrics.

scenario:iast_aspects-ospathbasename_aspect

• 🟥 execution_time [+484.605ns; +535.410ns] or [+14.886%; +16.446%]

scenario:iast_aspects-ospathsplit_aspect

• 🟥 execution_time [+483.347ns; +550.696ns] or [+12.678%; +14.444%]

[romainkomorndatadog]

LGTM from the CI Visibility side.

[datadog-dd-trace-py-rkomorn]

Datadog Report

Branch report: munir/fix-type-checking-for-telemetry-namespace
Commit report: c9dcd02
Test service: dd-trace-py

✅ 0 Failed, 863 Passed, 605 Skipped, 15m 3.63s Total duration (20m 33.36s time saved)