fdo#80084 file driver PreparedStatement: close previous ResultSet on reexec

This partially reverts commit d87c2c59c9c1d5f5825f355c9eb941fdf95b42f6
"sdbc file driver (Prepared)Statement: created ResultSet owned by *caller*"

From that commit, we keep the part about not reusing the same
ResultSet on reexecution (client code may have disposed it or closed
it), but we revert the part about not closing / disposing the previous
ResultSet on reexecution.

Change-Id: I4946207f9740484b2f5fbc3575a5708fe39f357c