SearchContext: remove unused variable (#79917)

remove rewritten member in SearchContext as it isn't used anywhere.

Author: Hendrik Muhs

server/src/main/java/org/elasticsearch/search/internal/SearchContext.java

@@ -66,7 +66,6 @@ public abstract class SearchContext implements Releasable {
     private final AtomicBoolean closed = new AtomicBoolean(false);
     private InnerHitsContext innerHitsContext;
 
-    private boolean rewritten;
     private Query rewriteQuery;
 
     protected SearchContext() {}