GH-8967: maxFetchSize = 1 from the StandardRotationPolicy

Fixes: #8967

In the `fair` mode the `StandardRotationPolicy` re-configures an `AbstractFetchLimitingMessageSource`
for a new directory (and possible new `ConnectionFactory`) in the `beforeReceive()`.
However, with default `maxFetchSize` (or bigger than `1`), the `receive()`` would poll `toBeReceived` internal queue
 for files cached from the previous polling cycle.
Since we rotate the source immediately to a new set of options, all those cached files make no sense
or even can cause the problem on fetching their content in case of `AbstractRemoteFileStreamingMessageSource`
when we rotate to a new `ConnectionFactory`.

* Call `fetchLimitingMessageSource.setMaxFetchSize(1);` in the `StandardRotationPolicy.beforeReceive()`
when `fair && !this.initialized`

**Auto-cherry-pick to `6.1.x`**

spring-integration-ftp/src/test/java/org/springframework/integration/ftp/inbound/RotatingServersTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-2023 the original author or authors.
+ * Copyright 2018-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -405,8 +405,7 @@ public class RotatingServersTests extends FtpTestSupport {
 		public IntegrationFlow flow() {
 			return IntegrationFlow.from(Ftp.inboundStreamingAdapter(new FtpRemoteFileTemplate(sf()))
 									.filter(new FtpPersistentAcceptOnceFileListFilter(new SimpleMetadataStore(), "rotate"))
-									.remoteDirectory(".")
-									.maxFetchSize(1),
+									.remoteDirectory("."),
 							e -> e.poller(Pollers.fixedDelay(1).advice(advice())))
 					.channel(MessageChannels.queue("files"))
 					.get();