[FIX] mail, *: significantly reduce number of useless renders

* = hr_holidays, im_livechat, website_livechat

A huge amount of components where rendered for no reason, notably when typing a
new message (at every key press), which significantly slowed down the interface.

There were 2 causes to this number of renders:
- OWL rendering all children automatically, even if their props didn't change,
  unless `shouldUpdate` is overridden, which is now done.
- `useStore` selectors being way too generous in what they observed

task-2399731

closes odoo/odoo#62703

Signed-off-by: Alexandre Kühn (aku) <aku@odoo.com>

1 files changed, 3 insertions, 4 deletions

diff --git a/addons/hr_holidays/static/src/components/thread_view/thread_view.js b/addons/hr_holidays/static/src/components/thread_view/thread_view.js
index c07ab2189a9..73ca28d4d0c 100644
--- a/addons/hr_holidays/static/src/components/thread_view/thread_view.js
+++ b/addons/hr_holidays/static/src/components/thread_view/thread_view.js
@@ -17,11 +17,10 @@ patch(components.ThreadView, 'hr_holidays/static/src/components/thread_view/thre
      */
     _useStoreSelector(props) {
         const res = this._super(...arguments);
-        const threadView = this.env.models['mail.thread_view'].get(props.threadViewLocalId);
-        const thread = threadView ? threadView.thread : undefined;
-        const correspondent = thread ? thread.correspondent : undefined;
+        const thread = res.thread;
+        const correspondent = thread && thread.correspondent;
         return Object.assign({}, res, {
-            correspondent: correspondent ? correspondent.__state : undefined,
+            correspondentOutOfOfficeText: correspondent && correspondent.outOfOfficeText,
         });
     },
 });