gsettings test: fix srcdir != builddir

Just copy the schemas to the builddir and compile them in place instead
of trying to mess around with creating the compiled file in a different
dir.  This solves issues in the summary/description testcase when
GSettings expects the usual situation of having the .xml files present
in the same directory.
Revert "gdbus-connection-loss: Fix leak in test"

This reverts commit 670379b26f4a86c7b51b928eb0332b9a654e4c4c.

This is causing distcheck to fail and will have to be revisited later.
GLib 2.39.1