[FIX] website: properly mark carousel test tour as a test tour

Commit [1] and its forward-ports introduced a test tour (properly added
in assets_tests) but was not declared as a test one. Meaning that if you
were in debug=tests, you were able to follow a strange tour not meant
for user testing.

[1]: https://github.com/odoo/odoo/commit/3c194faa930b0d3a537ca8b893b2c0442b5464e7



closes odoo/odoo#80354

Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>