* issue: make the 1.3.0 upgrade resilient when user_domains tables are already removed
A forced upgrade re-run (e.g. --forcever) after the login_providers migration has dropped user_domains/user_domains_ldap previously failed hard on the raw ALTER TABLE statements, because the guards only checked db_column_exists() (which returns false when the whole table is gone). Guard the three ADD COLUMN statements with db_table_exists(), and make ldap_convert_1_3_0() return early when user_domains_ldap no longer exists, so the MODIFY COLUMN and subsequent legacy operations are skipped. The upgrade now tolerates the re-run as intended.
* changelog: 8190.issue fragment for upgrade resilience fix
* Add regression coverage for the 1.3.0 user_domains table guards
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Co-authored-by: TheWitness <TheWitness@users.noreply.github.com>
Co-authored-by: TheWitness <copilot@users.noreply.github.com>
