[FIX] web_editor: update value only when dirty

Before this commit
The method `updateValue` was updating value constantly
because `value` was a string and `this.props.value` a Markup.

Now
Update only when necessary

closes odoo/odoo#100965

X-original-commit: 45d4ac14f65c53dcde56592715d50169bde116ad
Signed-off-by: Antoine Guenet (age) <age@odoo.com>

addons/web_editor/static/src/js/backend/html_field.js

@@ -186,7 +186,7 @@ export class HtmlField extends Component {
     }
     updateValue() {
         const value = this.getEditingValue();
-        if (value !== null && value !== this.props.value) {
+        if (value !== null && value !== (this.props.value || '').toString()) {
             if (this.props.setDirty) {
                 this.props.setDirty(true);
             }