Add migration validator to make sure ignore_column is present in model

Terri Churequested to merge
512095-add-test-for-dropping-columns into master

What does this MR do and why?

This MR adds a new validation to the migration schema validator. The new validator only checks migrations introduced in the MR. It validates that the associated model has the ignore_column(s) for the removed columns or the pipeline fails.

References

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MR acceptance checklist

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Screenshots or screen recordings

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How to set up and validate locally

  1. Commit one or more post deploy migrations to remove columns
  2. Run the validation script

pipeline failure example: https://gitlab.com/gitlab-org/gitlab/-/jobs/8821888519#L199

❯ RAILS_ENV=development scripts/validate_migration_schema
$ git merge-base master HEAD
a4646cff84dd0eefe9c3c602464d7d65c640a4cd

$ git diff --name-only --diff-filter=A a4646cff84dd0eefe9c3c602464d7d65c640a4cd -- db/migrate db/post_migrate
db/post_migrate/20250108141455_remove_column_from_table.rb
db/post_migrate/20250109154838_remove_more_columns_test.rb

Error: Column operations, like dropping, renaming or primary key conversion, require columns to be ignored in
the model. This step is necessary because Rails caches the columns and re-uses it in various places across the
application. Refer to these pages for more information:

https://docs.gitlab.com/ee/development/database/avoiding_downtime_in_migrations.html#dropping-columns
https://docs.gitlab.com/ee/development/database/avoiding_downtime_in_migrations.html#renaming-columns
https://docs.gitlab.com/ee/development/database/avoiding_downtime_in_migrations.html#migrating-integer-primary-keys-to-bigint

Please ensure that columns are properly ignored in the models

ApplicationSetting: elasticsearch_aws, elasticsearch_search
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Search::Zoekt::Node: metadata
Edited by Terri Chu

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