Fix typo

Signed-off-by: Gao Binlong <gbinlong@amazon.com>

server/src/main/java/org/opensearch/search/backpressure/settings/SearchShardTaskSettings.java

@@ -53,7 +53,7 @@ private static class Defaults {
                 throw new IllegalArgumentException("search_backpressure.search_shard_task.cancellation_ratio must be > 0");
             }
             if (value > 1.0) {
-                throw new IllegalArgumentException("search_backpressure.search_shard_task.cancellation_ratio must <= 1.0");
+                throw new IllegalArgumentException("search_backpressure.search_shard_task.cancellation_ratio must be <= 1.0");
             }
         },
         Setting.Property.Dynamic,