AdjustUpgrade.pm should zap test_ext_cine, too.

test_extensions' test_ext_cine extension has the same upgrade hazard
as test_ext7: the regression test leaves it in an updated state
from which no downgrade path to default is provided.  This causes
the update_extensions.sql script helpfully provided by pg_upgrade
to fail.  So drop it in cross-version-upgrade testing.

Not entirely sure how come I didn't hit this in testing yesterday;
possibly I'd built the upgrade reference databases with
testmodules-install-check disabled.

Backpatch to v10 where this module was introduced.

src/test/perl/PostgreSQL/Test/AdjustUpgrade.pm

@@ -88,12 +88,13 @@ sub adjust_database_contents
 		}
 	}
 
-	# avoid version number issues with test_ext7
+	# avoid no-path-to-downgrade-extension-version issues
 	if ($dbnames{contrib_regression_test_extensions})
 	{
 		_add_st(
 			$result,
 			'contrib_regression_test_extensions',
+			'drop extension if exists test_ext_cine',
 			'drop extension if exists test_ext7');
 	}