Remove more dead code

ConflictSet.cpp

@@ -1834,9 +1834,7 @@ struct CheckRangeLeftSide {
           remaining =
               remaining.subspan(commonLen, remaining.size() - commonLen);
         } else if (n->partialKeyLen > int(remaining.size())) {
-          if (searchPathLen < prefixLen) {
-            return downLeftSpine();
-          }
+          assert(searchPathLen >= prefixLen);
           if (n->entryPresent && n->entry.rangeVersion > readVersion) {
             ok = false;
             return true;