Set the level for zstd best speed to 1

This change sets the zstd best speed level from 0 to 1.
Compression level 0 means the default level will be used, which is level 3.
The intent of speed is to use the fastest compression level so 1 is a more appropriate value.
Note that zstd best speed is still under a feature flag so this change is just meant to evaluate the impact on our nightly benchmarks.
Further testing is needed (wip) to remove the feature flag entirely.

Author: jimczi

server/src/main/java/org/elasticsearch/index/codec/zstd/Zstd814StoredFieldsFormat.java

@@ -48,7 +48,7 @@ public final class Zstd814StoredFieldsFormat extends Lucene90CompressingStoredFi
     public static final String MODE_KEY = Zstd814StoredFieldsFormat.class.getSimpleName() + ".mode";
 
     public enum Mode {
-        BEST_SPEED(0, BEST_SPEED_BLOCK_SIZE, 128),
+        BEST_SPEED(1, BEST_SPEED_BLOCK_SIZE, 128),
         BEST_COMPRESSION(3, BEST_COMPRESSION_BLOCK_SIZE, 2048);
 
         final int level, blockSizeInBytes, blockDocCount;