Remove Dead Code from Snapshot Shard Assignment Logic (#58793)

Now that the init phase is gone from snapshots we do the index resolution and the shard
assignment in the same CS update so it's impossible to not find any routing data for an index
name that we resolved from the same CS.

server/src/main/java/org/elasticsearch/snapshots/SnapshotsService.java

@@ -1240,7 +1240,8 @@ public class SnapshotsService extends AbstractLifecycleComponent implements Clus
                 builder.put(new ShardId(indexName, IndexMetadata.INDEX_UUID_NA_VALUE, 0),
                     new SnapshotsInProgress.ShardSnapshotStatus(null, ShardState.MISSING, "missing index", null));
             } else {
-                IndexRoutingTable indexRoutingTable = clusterState.getRoutingTable().index(indexName);
+                final IndexRoutingTable indexRoutingTable = clusterState.getRoutingTable().index(indexName);
+                assert indexRoutingTable != null;
                 for (int i = 0; i < indexMetadata.getNumberOfShards(); i++) {
                     ShardId shardId = new ShardId(indexMetadata.getIndex(), i);
                     final String shardRepoGeneration;
@@ -1255,27 +1256,20 @@ public class SnapshotsService extends AbstractLifecycleComponent implements Clus
                     } else {
                         shardRepoGeneration = null;
                     }
-                    if (indexRoutingTable != null) {
-                        ShardRouting primary = indexRoutingTable.shard(i).primaryShard();
-                        if (primary == null || !primary.assignedToNode()) {
-                            builder.put(shardId,
-                                new SnapshotsInProgress.ShardSnapshotStatus(null, ShardState.MISSING, "primary shard is not allocated",
-                                    shardRepoGeneration));
-                        } else if (primary.relocating() || primary.initializing()) {
-                            builder.put(shardId, new SnapshotsInProgress.ShardSnapshotStatus(
-                                primary.currentNodeId(), ShardState.WAITING, shardRepoGeneration));
-                        } else if (!primary.started()) {
-                            builder.put(shardId,
-                                new SnapshotsInProgress.ShardSnapshotStatus(primary.currentNodeId(), ShardState.MISSING,
-                                    "primary shard hasn't been started yet", shardRepoGeneration));
-                        } else {
-                            builder.put(shardId,
-                                new SnapshotsInProgress.ShardSnapshotStatus(primary.currentNodeId(), shardRepoGeneration));
-                        }
+                    final ShardSnapshotStatus shardSnapshotStatus;
+                    ShardRouting primary = indexRoutingTable.shard(i).primaryShard();
+                    if (primary == null || !primary.assignedToNode()) {
+                        shardSnapshotStatus =
+                            new ShardSnapshotStatus(null, ShardState.MISSING, "primary shard is not allocated", shardRepoGeneration);
+                    } else if (primary.relocating() || primary.initializing()) {
+                        shardSnapshotStatus = new ShardSnapshotStatus(primary.currentNodeId(), ShardState.WAITING, shardRepoGeneration);
+                    } else if (!primary.started()) {
+                        shardSnapshotStatus = new ShardSnapshotStatus(primary.currentNodeId(), ShardState.MISSING,
+                            "primary shard hasn't been started yet", shardRepoGeneration);
                     } else {
-                        builder.put(shardId, new SnapshotsInProgress.ShardSnapshotStatus(null, ShardState.MISSING,
-                            "missing routing table", shardRepoGeneration));
+                        shardSnapshotStatus = new ShardSnapshotStatus(primary.currentNodeId(), shardRepoGeneration);
                     }
+                    builder.put(shardId, shardSnapshotStatus);
                 }
             }
         }