Add functional tests for apply_default_uniqueness_rules using database-backed assertions

[rijulpoudel]

specify7/specifyweb/specify/management/commands/tests/business_rules_tests.py

Lines 61 to 70 in 9d65f24

	fake_apps = FakeApps()
	with patch.object(rkm, "apply_default_uniqueness_rules") as apply_rules:
	rkm.apply_default_uniqueness_rules_to_disciplines(fake_apps)
	apply_rules.assert_called_once_with(
	discipline_without_constraint,
	registry=fake_apps,
	)
	self.assertIs(fake_uniqueness_rule_manager.last_is_database_constraint, True)

The existing test for apply_default_uniqueness_rules_to_disciplines in
business_rules_tests.py only verifies control flow, that the outer function
calls apply_default_uniqueness_rules once. There are no tests that actually
verify the behavior end-to-end.

We need database-backed tests that confirm:

• Uniqueness Rules are actually created in Disciplines that don't have them
• Duplicate rules are NOT created in Disciplines that already have the rules
• apply_default_uniqueness_rules_to_disciplines only targets Disciplines
  without existing Uniqueness Rules, skipping those that already have them

Originally posted by @melton-jason in #8225 (comment)