Remove caching of tasks, faults and operations

No longer seems to provide significant performance benefit to justify the
drawback of the added code complexity and the additional DB write query.

lib/api-functions.ts

@@ -367,7 +367,6 @@ export async function deleteDevice(deviceId: string): Promise<void> {
         $regex: `^${common.escapeRegExp(deviceId)}\\:`,
       },
     }),
-    cache.del(`${deviceId}_tasks_faults_operations`),
   ]);
 }
 
@@ -387,7 +386,6 @@ export async function deleteResource(
     if (channel.startsWith("task_"))
       proms.push(deleteTask(new ObjectId(channel.slice(5))));
     await Promise.all(proms);
-    await cache.del(`${deviceId}_tasks_faults_operations`);
   } else if (resource === "provisions") {
     await deleteProvision(id);
     await cache.del("cwmp-local-cache-hash");
@@ -439,8 +437,6 @@ export async function postTasks(
     };
   }
 
-  await cache.del(`${deviceId}_tasks_faults_operations`);
-
   const status = await connectionRequest(deviceId, device);
 
   if (status) {