CNDB-15207 test ED as default

Sets default SAI version to ED.

Author: k-rus

src/java/org/apache/cassandra/config/CassandraRelevantProperties.java

@@ -358,7 +358,7 @@ public enum CassandraRelevantProperties
     CUSTOM_SSTABLE_WATCHER("cassandra.custom_sstable_watcher"),
 
     /** The current version of the SAI on-disk index format. */
-    SAI_CURRENT_VERSION("cassandra.sai.latest.version", "ec"),
+    SAI_CURRENT_VERSION("cassandra.sai.latest.version", "ed"),
 
     /** Controls the maximum top-k limit for vector search */
     SAI_VECTOR_SEARCH_MAX_TOP_K("cassandra.sai.vector_search.max_top_k", "1000"),