fix(autofix): Dual-delete Seer preferences for disabled repositories

[srest2021]

Remove SeerProjectRepository rows and call /v1/project-preference/bulk-remove-repositories Seer endpoint for disabled repositories. This covers more of Seer's deletion task cleanup_stale_seer_preferences_task, as part of the migration of Seer settings from Seer to Sentry (spec).

[github-actions]

Backend Test Failures

Failures on d99cb0c in this run:

tests/sentry/integrations/github/test_webhook.py::InstallationRepositoriesEventWebhookTest::test_end_to_end_repos_removed — log

[gw1] linux -- Python 3.13.1 /home/runner/work/sentry/sentry/.venv/bin/python3
tests/sentry/integrations/github/test_webhook.py:495: in test_end_to_end_repos_removed
    assert response.status_code == 204
E   assert 500 == 204
E    +  where 500 = <Response status_code=500, "application/json">.status_code

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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