fix(idempotency): revert dict mutation that impacted static_pk_value feature

[heitorlessa]

Issue number: #1968

NOTE: This is literally a contribution from @Tankanow. Had to cut a PR to get it merged quicker due to the regression.

Summary

Changes

Please provide a summary of what's being changed

Reverts a regression added in #1899 when making DynamoDB client thread-safe.

static_pk_value is used by customers using Single Table design pattern with DynamoDB, where a composite key is used with a static value for its "primary key" attr. This change reverts a dictionary mutation that discarded the value from static_pk_value and used key_id instead.

In simple terms, same effect as:

a = {"my_key": "must_be_static"}
b = {
    **a,
    "my_key": "this is the final value"  # this shouldn't exist as it'll always win last insertion
}

User experience

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

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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[codecov-commenter]

Codecov Report

Patch coverage has no change and project coverage change: +0.01 🎉

Comparison is base (a318e8e) 97.43% compared to head (f87778a) 97.44%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1970      +/-   ##
===========================================
+ Coverage    97.43%   97.44%   +0.01%     
===========================================
  Files          146      146              
  Lines         6660     6660              
  Branches       478      478              
===========================================
+ Hits          6489     6490       +1     
  Misses         134      134              
+ Partials        37       36       -1     

Impacted Files	Coverage Δ
...ools/utilities/idempotency/persistence/dynamodb.py	100.00% <ø> (+1.23%)	⬆️

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[Tankanow]

I don't have the power, but FWIW, Approved. 😄

[heitorlessa]

Added co-authorship to the merge commit but as your email isn't public the no-reply might not credit it correctly (I'll do in the release regardless)

ca9686d