fix(fab): Align ORM column sizes with migration definitions

[Jie211]

This PR try to fixes the inconsistency between ORM model definitions and Alembic migration definitions in the FAB provider

• closes: ORM and Migration have inconsistent column sizes for ab_user.first_name/last_name #60863

Problem

When FAB 5 support was added , db.create_all() was introduced in create_db_from_orm().
This causes tables to be created using ORM metadata instead of migrations when initializing a fresh database.

The ORM defines different column sizes than the migration:

Column	ORM	Migration
ab_user.first_name	String(64)	String(256)
ab_user.last_name	String(64)	String(256)
ab_user.email	String(320)	String(512)

This PR

Align the ORM column definitions to match the migration definitions.

I understand there might be alternative approaches to solve this issue (like modifying create_db_from_orm() to run migrations instead of using ORM metadata), but I believe aligning the ORM with the migration is the simplest and most straightforward fix.(not sure...)

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[vincbeck]

Thanks

[boring-cyborg]

Awesome work, congrats on your first merged pull request! You are invited to check our Issue Tracker for additional contributions.