fix: disable SQLite FK checks in 0111 migration downgrade

[Lee-W]

---

Why

SQLite doesn't support altering tables with foreign keys enabled. batch_alter_table recreates the dag table during drop_column, so the downgrade fails on SQLite without first disabling FK checks.

What

Wrap the drop_column with disable_sqlite_fkeys(op), matching other migrations that alter dag.

Was generative AI tooling used to co-author this PR?

• Yes (please specify the tool below)

---

• Read the Pull Request Guidelines for more information. Note: commit author/co-author name and email in commits become permanently public when merged.
• For fundamental code changes, an Airflow Improvement Proposal (AIP) is needed.
• When adding dependency, check compliance with the ASF 3rd Party License Policy.
• For significant user-facing changes create newsfragment: {pr_number}.significant.rst, in airflow-core/newsfragments. You can add this file in a follow-up commit after the PR is created so you know the PR number.