Before this commit, the `test_websocket_instances_weak_set` was sometimes failing. Indeed, this test doesn't wait for the connection to be fully established before making its assertions. This commit fixes this issue. fixes runbot-55037,55035 closes odoo/odoo#157510 X-original-commit: 15bad5ccbeced41127eeaea3e47eebbc3f55091e Signed-off-by: Matthieu Stockbauer (tsm) <tsm@odoo.com>