fix(logger): clear_state should keep custom key formats

[eliasbrange]

Issue #, if available: #1084

Description of changes:

When using clear_state=True, overriden formats for standard logging keys like location and timestamp was being overriden with the default formats. Overriding the formats are explained in the docs like this:

from aws_lambda_powertools import Logger

date_format = "%m/%d/%Y %I:%M:%S %p"
location_format = "[%(funcName)s] %(module)s"

# override location and timestamp format
logger = Logger(service="payment", location=location_format, datefmt=date_format)

Issue was that when clear_state=True was used, the default keys were reset to their defaults (by the fix implemented in #1088). This fix saves the formatting keys on instantiation and uses those instead when clear_state is called.

Checklist

• Meet tenets criteria
• Update tests
• Update docs
• PR title follows conventional commit semantics

Breaking change checklist

RFC issue #:

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

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[boring-cyborg]

Thanks a lot for your first contribution! Please check out our contributing guidelines and don't hesitate to ask whatever you need.

[codecov-commenter]

Codecov Report

Merging #1095 (4318dcc) into develop (f24332d) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff            @@
##           develop    #1095   +/-   ##
========================================
  Coverage    99.96%   99.96%           
========================================
  Files          119      119           
  Lines         5377     5377           
  Branches       613      613           
========================================
  Hits          5375     5375           
  Partials         2        2           

Impacted Files	Coverage Δ
aws_lambda_powertools/logging/formatter.py	100.00% <100.00%> (ø)

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[heitorlessa]

one suggestion on tests so we reduce the use of regex to improve test perf and ease future maintenance for the untrained eye.

[boring-cyborg]

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