refactor(di): simplify context capturing API

[P403n1x87]

We clean up the internal context capturing API after the recent changes that have introduced support for local variables in function probes and the exposure of globals to expression/condition evaluations.

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

[datadog-dd-trace-py-rkomorn]

Datadog Report

Branch report: refactor/di-simplify-capture-context-api
Commit report: 5442b55
Test service: dd-trace-py

✅ 0 Failed, 1114 Passed, 368 Skipped, 1m 23.73s Total Time

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-08-30 11:42:54

Comparing candidate commit 5442b55 in PR branch refactor/di-simplify-capture-context-api with baseline commit 4f1a3da in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 353 metrics, 47 unstable metrics.

[github-actions]

CODEOWNERS have been resolved as:

ddtrace/debugging/_debugger.py                                          @DataDog/debugger-python
ddtrace/debugging/_probe/model.py                                       @DataDog/debugger-python
ddtrace/debugging/_signal/metric_sample.py                              @DataDog/debugger-python
ddtrace/debugging/_signal/model.py                                      @DataDog/debugger-python
ddtrace/debugging/_signal/snapshot.py                                   @DataDog/debugger-python
ddtrace/debugging/_signal/tracing.py                                    @DataDog/debugger-python
tests/debugging/signal/test_collector.py                                @DataDog/debugger-python
tests/debugging/signal/test_model.py                                    @DataDog/debugger-python
tests/debugging/test_debugger.py                                        @DataDog/debugger-python
tests/debugging/test_encoding.py                                        @DataDog/debugger-python