fix(batch): bugfix to clear exceptions between executions

[michaelbrewer]

Issue #, if available:

closes #1021

Description of changes:

Changes:

• Add failing test
• Add part of _prepare we should also clear the exceptions list, so that cold starts and warm starts behave the same.

Checklist

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

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[codecov-commenter]

Codecov Report

Merging #1022 (0475b5d) into develop (77f86c0) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff            @@
##           develop    #1022   +/-   ##
========================================
  Coverage    99.96%   99.96%           
========================================
  Files          119      119           
  Lines         5364     5365    +1     
  Branches       612      612           
========================================
+ Hits          5362     5363    +1     
  Partials         2        2           

Impacted Files	Coverage Δ
aws_lambda_powertools/utilities/batch/base.py	99.21% <100.00%> (+<0.01%)	⬆️

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