[Release] Fixes around threads beta in degraded mode (#8319)

* Fix soft crash around the thread panel in degraded mode

* Better specify fallback key

* Hide MAB Threads prompt if user would have degraded mode

* Confirm user wants to enable Threads beta if in degraded mode

* Fix copy

src/components/structures/ThreadPanel.tsx

@@ -286,7 +286,7 @@ const ThreadPanel: React.FC<IProps> = ({
                 />
                 { timelineSet && (
                     <TimelinePanel
-                        key={timelineSet.getFilter().filterId}
+                        key={timelineSet.getFilter()?.filterId ?? (roomId + ":" + filterOption)}
                         ref={timelinePanel}
                         showReadReceipts={false} // No RR support in thread's MVP
                         manageReadReceipts={false} // No RR support in thread's MVP