[DOP-22429] Prefer if_exists=... over mode=...

[dolfinus]

Change Summary

Due to pydantic/pydantic#5893, VSCode prefers alias over original field name:

But in some places we use alias=... for legacy field name, and original field name should be preferred:

Related issue number

Checklist

• Commit message and PR title is comprehensive
• Keep the change as small as possible
• Unit and integration tests for the changes exist
• Tests pass on CI and coverage does not decrease
• Documentation reflects the changes where applicable
• docs/changelog/next_release/<pull request or issue id>.<change type>.rst file added describing change
  (see CONTRIBUTING.rst for details.)
• My PR is ready to review.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.51%. Comparing base (179bf5c) to head (4f35d5f).
Report is 3 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #354      +/-   ##
===========================================
+ Coverage    92.50%   92.51%   +0.01%     
===========================================
  Files          228      229       +1     
  Lines         9918     9932      +14     
  Branches      1014     1014              
===========================================
+ Hits          9175     9189      +14     
  Misses         557      557              
  Partials       186      186              

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