The previous location was /usr/etc/syncevolution. It should have been
/etc/syncevolution in our debs, with proper declaration as system
config files. The intention was that system admins can add or modify
templates.

Not particularly likely, so now template files are only searched in
/usr/share/syncevolution/templates (or whatever was chosen with
configure --datadir).

Also added a README to that directory, warning that copying these
files will lead to incomplete configs. Each main config.ini carries
a similar comment, for those who miss the README.