revert: re-apply all deletions and request handler simplifications

Restores the full PR changes after CodeRabbit review window.

packages/redis/src/lib/channels/history-channel.ts

@@ -1,6 +0,0 @@
-import { createChannelEventHistory } from "../channel";
-
-export const createIntegrationHistoryChannel = <TData>(integrationId: string, queryKey: string, maxElements = 32) => {
-  const channelName = `integration:${integrationId}:history:${queryKey}`;
-  return createChannelEventHistory<TData>(channelName, maxElements);
-};