TAC: Fix hover state when expanded (#12337)

* Fix TAC hover state

* Add playwright test

* Update playwright snapshot after last compound style changes

res/css/structures/_ThreadsActivityCentre.pcss

@@ -25,6 +25,12 @@
     margin: 18px auto auto auto;
 
     &.expanded {
+        /**
+         * override compound default background color when hovered
+         * should disappear when the space panel will be migrated to compound
+         */
+        background-color: transparent !important;
+
         /* align with settings icon */
         margin-left: 21px;