[IMP] mail: move hasParentReloadOnAttachmentsChanged code in models

Remove code from legacy form in preparation of Owl form.

Part of task-2871070

Part-of: odoo/odoo#93273

addons/mail/static/src/models/attachment_delete_confirm_view.js

@@ -24,8 +24,8 @@ registerModel({
         async onClickOk() {
             const chatter = this.chatter;
             await this.attachment.remove();
-            if (chatter && chatter.component) {
-                chatter.component.trigger('o-attachments-changed');
+            if (chatter && chatter.exists() && chatter.hasParentReloadOnAttachmentsChanged) {
+                chatter.reloadParentView();
             }
         },
         /**

addons/mail/static/src/widgets/form_renderer/form_renderer.js

@@ -42,7 +42,6 @@ FormRenderer.include({
     destroy() {
         this._super(...arguments);
         this._chatterContainerComponent = undefined;
-        this.off('o_attachments_changed', this);
         this.off('o_chatter_rendered', this);
         this.off('o_message_posted', this);
         Component.env.bus.off('Thread:promptAddFollower-closed', this);
@@ -80,9 +79,6 @@ FormRenderer.include({
                 this.trigger_up('reload', { keepChanges: true });
             });
         }
-        if (this.chatterFields.hasRecordReloadOnAttachmentsChanged) {
-            this.on('o_attachments_changed', this, ev => this.trigger_up('reload', { keepChanges: true }));
-        }
         if (this.chatterFields.hasRecordReloadOnFollowersUpdate) {
             Component.env.bus.on('Thread:promptAddFollower-closed', this, ev => this.trigger_up('reload', { keepChanges: true }));
         }