Remove duplicated assert in test (opensearch-project#12616)

This line can be safely removed because the two lines following
this assert test exactly the same condition.

Signed-off-by: Lukáš Vlček <lukas.vlcek@aiven.io>

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

@@ -298,7 +298,6 @@ public void testGatewayRecovery() throws Exception {
         logger.info("--> request recoveries");
         RecoveryResponse response = client().admin().indices().prepareRecoveries(INDEX_NAME).execute().actionGet();
         assertThat(response.shardRecoveryStates().size(), equalTo(SHARD_COUNT));
-        assertThat(response.shardRecoveryStates().get(INDEX_NAME).size(), equalTo(1));
 
         List<RecoveryState> recoveryStates = response.shardRecoveryStates().get(INDEX_NAME);
         assertThat(recoveryStates.size(), equalTo(1));