feat(metrics): warn when overwriting dimension

[anafalcao]

Issue number:
#5638

Summary

Changes

Please provide a summary of what's being changed

When using dimensions with the Metrics class, the default behavior is to overwrite existing dimensions if a new dimension with the same name/key is added. To improve troubleshooting and prevent silent data loss, we've implemented a warning system that alerts users when dimension overwriting occurs.

User experience

Please share what the user experience looks like before and after this change

from aws_lambda_powertools.metrics import Metrics

metrics = Metrics(namespace="MyApp")

metrics.add_dimension(name="test", value="foo")
metrics.add_dimension(name="test", value="bar")  # "bar" replaces "foo"

# A warning is now issued:
# UserWarning: Dimension 'test' has already been added. The previous value will be overwritten.

Checklist

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• Meet tenets criteria
• I have performed a self-review of this change
• Changes have been tested
• Changes are documented
• PR title follows conventional commit semantics

Is this a breaking change?

RFC issue number:

Checklist:

• Migration process documented
• Implement warnings (if it can live side by side)

Acknowledgment

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Disclaimer: We value your time and bandwidth. As such, any pull requests created on non-triaged issues might not be successful.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.17%. Comparing base (fb245cc) to head (f7be51b).
Report is 2 commits behind head on develop.

Additional details and impacted files

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  Coverage    96.17%   96.17%           
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  Files          231      231           
  Lines        10916    10920    +4     
  Branches      2018     2019    +1     
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+ Hits         10498    10502    +4     
  Misses         329      329           
  Partials        89       89           

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[dreamorosi]

Thank you for implementing this quickly!