Fix and simplify testTargetThrottling (elastic#103397)

There seems to be two potential issues that can cause failure: 1. If
the`INDICES_RECOVERY_MAX_BYTES_PER_SEC_SETTING` on nodeA is too small,
then we might choose a chunk size on nodeB that can cause throttling on
nodeA.  2. At the end when we remove the throttling limits, it is
possible that first nodeB gets unthrottled which can cause nodeA
throttling recovery, it seems. 

Closes elastic#103204

server/src/internalClusterTest/java/org/elasticsearch/indices/recovery/IndexRecoveryIT.java

@@ -782,10 +782,13 @@ public Settings onNodeStopped(String nodeName) {
      * Tests shard recovery throttling on the target node. Node statistics should show throttling time on the target node, while no
      * throttling should be shown on the source node because the target will accept data more slowly than the source's throttling threshold.
      */
-    @AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/103204")
     public void testTargetThrottling() throws Exception {
         logger.info("--> starting node A with default settings");
-        final String nodeA = internalCluster().startNode();
+        final String nodeA = internalCluster().startNode(
+            Settings.builder()
+                // Use a high value so that when unthrottling recoveries we do not cause accidental throttling on the source node.
+                .put(RecoverySettings.INDICES_RECOVERY_MAX_BYTES_PER_SEC_SETTING.getKey(), "200mb")
+        );
 
         logger.info("--> creating index on node A");
         ByteSizeValue shardSize = createAndPopulateIndex(INDEX_NAME, 1, SHARD_COUNT_1, REPLICA_COUNT_0).getShards()[0].getStats()