Remove now unneeded waitForInitialItems TimelineProvider method.

ElementX/Sources/Services/Timeline/TimelineItemProvider.swift

@@ -66,17 +66,6 @@ class TimelineItemProvider: TimelineItemProviderProtocol {
         }
     }
     
-    /// A continuation to signal whether the initial timeline items have been loaded and processed.
-    private var hasLoadedInitialItemsContinuation: CheckedContinuation<Void, Never>?
-    /// A method that allows `await`ing the first update of timeline items from the listener, as the items
-    /// aren't added directly to the provider upon initialisation and may take some time to come in.
-    func waitForInitialItems() async {
-        guard itemProxies.isEmpty else { return }
-        return await withCheckedContinuation { continuation in
-            hasLoadedInitialItemsContinuation = continuation
-        }
-    }
-    
     // MARK: - Private
     
     private func updateItemsWithDiffs(_ diffs: [TimelineDiff]) {
@@ -101,11 +90,6 @@ class TimelineItemProvider: TimelineItemProviderProtocol {
             
             return updatedItems
         }
-        
-        if let hasLoadedInitialItemsContinuation {
-            hasLoadedInitialItemsContinuation.resume()
-            self.hasLoadedInitialItemsContinuation = nil
-        }
     }
     
     private func buildDiff(from diff: TimelineDiff, on itemProxies: [TimelineItemProxy]) -> CollectionDifference<TimelineItemProxy>? {