Fix subqueryload losing .and_() criteria with of_type()

Fix subqueryload losing .and_() criteria with of_type()

Fixed issue where subqueryload would silently ignore additional filter
criteria passed via .and_() when of_type() was also used. Two changes:

1. In _SubqueryLoader._setup_options(), use effective_entity instead of
   self.entity when creating the LoaderCriteriaOption, so that the criteria
   is associated with the correct polymorphic entity (e.g. the of_type()
   target). This matches the behavior of selectinload which already uses
   effective_entity.

2. In _JoinCondition.join_targets mark_exclude_cols(), add a mapper.isa()
   check so that subclass mapper columns are recognized as belonging to
   the relationship target. Previously, only the base class mapper was
   checked via identity comparison (is not self.prop.mapper), causing
   subclass columns to be annotated with should_not_adapt, which prevented
   the ClauseAdapter from rewriting them to use the subquery alias.

The same mapper.isa() fix also resolves #13203 (joinedload variant).

Fixes: #13207
Related: #13203