Before this commit, components used `el` and `trigger` but this works thanks to LegacyComponent. LegacyComponent has been introduced to ease the transition from owl 1 to owl 2. This commit replaces the uses of `el` by `useRef` and `trigger` by adding callback in props. Without these owl 1 features, components no longer need to extend LegacyComponent. This commit also adapts the tests to use `getFixture` instead of `el`. closes odoo/odoo#85903 Related: odoo/enterprise#25032 Signed-off-by: Samuel Degueldre <sad@odoo.com> Co-authored-by: Aaron Bohy <aab@odoo.com> Co-authored-by: Simon Genin (ges) <ges@odoo.com> Co-authored-by: luvi <luvi@odoo.com> Co-authored-by: Jorge Pinna Puissant <jpp@odoo.com>