networkAgent: Update VPN config path

The location moved a while ago, so update the path to point to
the non-deprecated location.

https://bugzilla.gnome.org/show_bug.cgi?id=791487

src/meson.build

@@ -13,7 +13,6 @@ script_data.set('libdir', libdir)
 script_data.set('libexecdir', libexecdir)
 script_data.set('pkgdatadir', pkgdatadir)
 script_data.set('pkglibdir', pkglibdir)
-script_data.set('sysconfdir', sysconfdir)
 script_data.set('PYTHON', python.path())
 script_data.set('VERSION', meson.project_version())