Remove classic mirrored queue docs for 4.x

The have been removed from rabbitmq/rabbitmq-server@main [1].

1. rabbitmq/rabbitmq-server#9815

Author: michaelklishin

docs/classic-queues.md

@@ -62,10 +62,8 @@ removal difficult to reason about in case of node restarts during upgrades and s
 so the use of transient queues is discouraged. Support for transient queues
 is deprecated and will be removed in **RabbitMQ 4.0**.
 
-Classic queues can be mirrored across multiple nodes in the
-cluster. This functionality is deprecated and will be removed
-in **RabbitMQ 4.0**. [Quorum queues](./quorum-queues)
-and [streams](./streams) provide a better alternative when high availability and
+Classic queues is a non-replicated queue type starting with RabbitMQ 4.0.
+[Quorum queues](./quorum-queues) and [streams](./streams) provide a better alternative when high availability and
 data safety is required.
 
 Until **RabbitMQ 3.12**, classic queues could operate in **lazy mode**.

docs/cluster-formation.md

@@ -464,7 +464,7 @@ to a value in the 5-10 second range.
 If a stateless set is used recreated nodes will not have their persisted data and will start as blank nodes.
 This can lead to data loss and higher network traffic volume due to more frequent
 data synchronisation of both [quorum queues](./quorum-queues)
-and [classic queue mirrors](./ha) on newly joining nodes.
+and [streams](./streams) on newly joining nodes.
 
 #### Use Persistent Volumes
 

docs/clustering.md

@@ -394,8 +394,7 @@ The [Quorum Queues guide](./quorum-queues) covers this topic in more detail.
 Assuming all cluster members
 are available, a messaging (AMQP 0-9-1, AMQP 1.0, MQTT, STOMP) client can connect to any node and
 perform any operation. Nodes will route operations to the
-[quorum queue leader](./quorum-queues) or [queue leader replica](./ha#leader-migration-data-locality)
-transparently to clients.
+[quorum queue leader](./quorum-queues) transparently to clients.
 
 With all supported messaging protocols a client is only connected to one node
 at a time.
@@ -410,10 +409,6 @@ for individual clients to learn more.
 With [quorum queues](./quorum-queues) and [streams](./streams), clients will only be able to perform
 operations on queues that have a quorum of replicas online.
 
-With classic mirrored queues, there are scenarios where it may not be possible for a client to transparently continue
-operations after connecting to a different node. They usually involve
-[non-mirrored queues hosted on a failed node](./ha#non-mirrored-queue-behavior-on-node-failure).
-
 ### Stream Clients
 
 RabbitMQ Stream protocol clients **behave differently from messaging protocols clients**: they are
@@ -508,7 +503,7 @@ known at the time of shutdown.
 across multiple cluster nodes with parallel replication and a predictable [leader election](./quorum-queues#leader-election)
 and [data safety](./quorum-queues#data-safety) behavior as long as a majority of replicas are online.
 
-Non-replicated classic queues can also be used in clusters. Non-mirrored queue [behaviour in case of node failure](./ha#non-mirrored-queue-behavior-on-node-failure)
+Non-replicated classic queues can also be used in clusters. Their behaviour in case of node failure
 depends on [queue durability](./queues#durability).
 
 RabbitMQ clustering has several modes of dealing with [network partitions](./partitions),

docs/configure.md

@@ -1290,20 +1290,6 @@ mnesia_table_loading_retry_limit = 10
     </td>
   </tr>
 
-  <tr>
-    <td>`mirroring_sync_batch_size`</td>
-    <td>
-      Batch size used to transfer messages to an unsynchronised replica (queue mirror).
-      See [documentation on eager batch synchronization](./ha#batch-sync).
-      <p>
-        Default:
-```ini
-mirroring_sync_batch_size = 4096
-```
-      </p>
-    </td>
-  </tr>
-
   <tr>
     <td>`queue_leader_locator`</td>
     <td>
@@ -1312,9 +1298,7 @@ mirroring_sync_batch_size = 4096
         <li>`balanced`</li>
         <li>`client-local`</li>
       </ul>
-      See the
-      [documentation
-      on queue leader location](./ha#queue-leader-location) for more information.
+
       <p>
         Default:
 ```ini

docs/feature-flags/index.md

@@ -421,14 +421,6 @@ The following feature flags are provided by RabbitMQ core.
       fix</a> to unblock a group of consumers in a super stream partition
     </td>
   </tr>
-  <tr>
-    <td>3.12.0</td>
-    <td>3.11.0</td>
-    <td>classic_mirrored_queue_version</td>
-    <td>
-      Support setting version for classic mirrored queues
-    </td>
-  </tr>
   <tr>
     <td>3.12.0</td>
     <td>3.11.0</td>