fix(api_gateway): fixed custom metrics issue when using debug mode

[pawosty]

Issue number: #1805

Summary

Changes

Newlines are now emitted at the end of api_gateway debug JSON events. This resolves an issue where the debug events would be combined with CloudWatch EMF metrics, resulting in the metrics being ignored.

User experience

Before, if debug mode was enabled in the api_gateway router, custom EMF metrics would be appended to the end of the debug JSON in the same line in standard out. This would result in the custom metrics being ignored by the CloudWatch agent. With this change, the two JSON objects are separated by newlines and CloudWatch recognizes the metrics data and uploads it.

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?

This is not a breaking change.

RFC issue number:

Checklist:

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

Acknowledgment

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[boring-cyborg]

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[codecov-commenter]

Codecov Report

Base: 97.58% // Head: 97.59% // Increases project coverage by +0.00% 🎉

Coverage data is based on head (f2298c3) compared to base (20ca7ed).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #1827   +/-   ##
========================================
  Coverage    97.58%   97.59%           
========================================
  Files          141      141           
  Lines         6425     6434    +9     
  Branches       442      444    +2     
========================================
+ Hits          6270     6279    +9     
  Misses         123      123           
  Partials        32       32           

Impacted Files	Coverage Δ
aws_lambda_powertools/event_handler/api_gateway.py	100.00% <100.00%> (ø)
...ws_lambda_powertools/utilities/idempotency/base.py	100.00% <100.00%> (ø)
...bda_powertools/utilities/idempotency/exceptions.py	100.00% <100.00%> (ø)

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[leandrodamascena]

Hi @pawosty! Great job catching and fixing this issue. Now I was able to simulate the problem with the current code this PR solves the problem.

Approved.

[boring-cyborg]

Awesome work, congrats on your first merged pull request and thank you for helping improve everyone's experience!