refactor: remove cycle in processor stats

[P403n1x87]

We remove a static circular import on typing in the processor stats module.

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/internal/processor/stats.py                                     @DataDog/apm-core-python

[github-actions]

Bootstrap import analysis

Comparison of import times between this PR and base.

Summary

The average import time from this PR is: 234 ± 4 ms.

The average import time from base is: 233 ± 3 ms.

The import time difference between this PR and base is: 0.7 ± 0.2 ms.

Import time breakdown

The following import paths have shrunk:

ddtrace.auto 1.825 ms (0.78%)

ddtrace.bootstrap.sitecustomize 1.165 ms (0.50%)

ddtrace.bootstrap.preload 1.165 ms (0.50%)

ddtrace.internal.products 1.165 ms (0.50%)

ddtrace.internal.remoteconfig.client 0.595 ms (0.25%)

ddtrace 0.660 ms (0.28%)

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-04-15 10:57:32

Comparing candidate commit ec6afc1 in PR branch refactor/processor-stats-cycle with baseline commit 717c54c in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 506 metrics, 2 unstable metrics.