chore(tracer): add more detail in encoding error message

[rachelyangdog]

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/_encoding.pyx                                          @DataDog/apm-core-python
tests/tracer/test_encoders.py                                           @DataDog/apm-sdk-api-python

[datadog-dd-trace-py-rkomorn]

Datadog Report

Branch report: rachel.yang/encoding-error
Commit report: 71be1f5
Test service: dd-trace-py

✅ 0 Failed, 1468 Passed, 0 Skipped, 24m 48.28s Total duration (13m 4.08s time saved)

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-02-11 20:39:39

Comparing candidate commit fa980d9 in PR branch rachel.yang/encoding-error with baseline commit 20b2b03 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 394 metrics, 2 unstable metrics.