[FIX] web_editor: correctly call onBlur on tab change

Before this commit, the onBlur function of snippet options was not
called if the blur occured because of a click on the 'Blocks' tab.

Part of https://github.com/odoo/odoo/pull/52081

X-original-commit: 85049e2dcf68c40218bd0f4ed7401a4f979951d4

addons/web_editor/static/src/js/editor/snippets.editor.js

@@ -2056,10 +2056,11 @@ var SnippetsMenu = Widget.extend({
      * @private
      */
     _onBlocksTabClick: function (ev) {
-        this._activateSnippet(false);
-        this._updateLeftPanelContent({
-            content: [],
-            tab: this.tabs.BLOCKS,
+        this._activateSnippet(false).then(() => {
+            this._updateLeftPanelContent({
+                content: [],
+                tab: this.tabs.BLOCKS,
+            });
         });
     },
     /**