Avoid unneeded save() in UnrestrictedSessionRunner

Today UnrestrictedSessionRunner does a lot of save() operations to propagate invalidations between the base session and the unrestricted one, in order to allow both sessions to see the same object. This is actually not needed as soon as we run with a JCA pool (i.e. everywhere except non-pooling unit tests), so I'll fix the code to not do them if not needed (it was working before for JBoss but the code got lost somehow).

A side effect is that unrestricted code that does session.query() and expect to see things not saved from the main session, or code where the unrestricted session does a change and the main session expects a query to see it, will not work anymore. Doing a save() before a query should be explicit in the code that needs it.