remove use of `LABEL_STYLE_TABLENAME_PLUS_COL` outside of Query

remove use of `LABEL_STYLE_TABLENAME_PLUS_COL` outside of Query

Changed the query style for ORM queries emitted by :meth:`.Session.get` as
well as many-to-one lazy load queries to use the default labeling style,
:attr:`_sql.SelectLabelStyle.LABEL_STYLE_DISAMBIGUATE_ONLY`, which normally
does not apply labels to columns in a SELECT statement. Previously, the
older style :attr:`_sql.SelectLabelStyle.LABEL_STYLE_TABLENAME_PLUS_COL`
that labels columns as `<tablename>_<columname>` was used for
:meth:`.Session.get` to maintain compatibility with :class:`_orm.Query`.
The change allows the string representation of ORM queries to be less
verbose in all cases outside of legacy :class:`_orm.Query` use. Pull
request courtesy Inada Naoki.

Fixes: #12932
Closes: #12926
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/12926
Pull-request-sha: 6738a73f635387b8326f546313cdfd12cf9ef5ab

Change-Id: I044a54226a4fcade07adc1a3f5f60b4b3e451a1e