chore(test-types): Add extra="forbid" to CamelModel; fix errors

[fselmo]

🗒️ Description

I'm still seeing issues from time to time where test writers (including myself) can misspell a kwarg to a test class which could go unnoticed with unintended consequences. This is an attempt to tighten up the pydantic models in our testing framework and prevent these sorts of issues.

• Use extra="forbid" in CamelModel which our test types inherit from
• Fix serialization issues by removing computed fields from input dicts on relevant models with singular field issues. For internal fixture models that use combined models to build a simpler model (many fields don't exist), explicitly turn on extra="allow" with a clarifying message on why we want to / need to do it here.
• Remove redundant model_config for classes that inherit from CamelModel

🔗 Related Issues or PRs

• Closes Add extra_forbid to CamelModel and fix errors #1612

✅ Checklist

• All: Ran fast tox checks to avoid unnecessary CI fails, see also Code Standards and Enabling Pre-commit Checks:

  uvx tox -e static

• All: PR title adheres to the repo standard - it will be used as the squash commit message and should start type(scope):.
• All: Considered adding an entry to CHANGELOG.md.
• All: Considered updating the online docs in the ./docs/ directory.
• All: Set appropriate labels for the changes (only maintainers can apply labels).

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.33%. Comparing base (9e56ac9) to head (4dc89fd).
⚠️ Report is 4 commits behind head on forks/amsterdam.

Additional details and impacted files

@@               Coverage Diff                @@
##           forks/amsterdam    #1989   +/-   ##
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  Coverage            86.33%   86.33%           
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  Files                  538      538           
  Lines                34557    34557           
  Branches              3222     3222           
================================================
  Hits                 29835    29835           
  Misses                4148     4148           
  Partials               574      574           

Flag	Coverage Δ
unittests	86.33% <ø> (ø)

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[marioevz]

LGTM, just one question of a change I didn't quite understand. Thanks!