Disable merge on refresh in DiskThresholdDeciderIT (#4828) (#4833)

Disables merge on refresh for DiskThresholdDeciderIT.testRestoreSnapshotAllocationDoesNotExceedWatermark.

Signed-off-by: Nicholas Walter Knize <nknize@apache.org>
(cherry picked from commit 49363fb)

CHANGELOG.md

@@ -93,6 +93,8 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - [Segment Replication] Fix timeout issue by calculating time needed to process getSegmentFiles ([#4434](https://github.com/opensearch-project/OpenSearch/pull/4434))
 - [Segment Replication] Update replicas to commit SegmentInfos instead of relying on segments_N from primary shards ([#4450](https://github.com/opensearch-project/OpenSearch/pull/4450))
 - [Segment Replication] Adding check to make sure checkpoint is not processed when a shard's shard routing is primary ([#4716](https://github.com/opensearch-project/OpenSearch/pull/4716))
+- Disable merge on refresh in DiskThresholdDeciderIT ([#4828](https://github.com/opensearch-project/OpenSearch/pull/4828))
+
 ### Security
 
 [Unreleased]: https://github.com/opensearch-project/OpenSearch/compare/2.2.0...HEAD

server/src/internalClusterTest/java/org/opensearch/cluster/routing/allocation/decider/DiskThresholdDeciderIT.java

@@ -217,6 +217,7 @@ public void testRestoreSnapshotAllocationDoesNotExceedWatermark() throws Excepti
                 .put(IndexMetadata.SETTING_NUMBER_OF_REPLICAS, 0)
                 .put(IndexMetadata.SETTING_NUMBER_OF_SHARDS, 6)
                 .put(INDEX_STORE_STATS_REFRESH_INTERVAL_SETTING.getKey(), "0ms")
+                .put(IndexSettings.INDEX_MERGE_ON_FLUSH_ENABLED.getKey(), false)
                 .build()
         );
         final long minShardSize = createReasonableSizedShards(indexName);