Clean out log files from testing the xml backend.

Otherwise make distcheck whines about them.

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@23373 57a11ea4-9604-0410-9ed3-97b8803252fd
Release 2.5.7

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@23374 57a11ea4-9604-0410-9ed3-97b8803252fd