all: simplify and fix database iteration with prefix/start (#20808)

* core/state/snapshot: start fixing disk iterator seek

* ethdb, rawdb, leveldb, memorydb: implement iterators with prefix and start

* les, core/state/snapshot: iterator fixes

* all: remove two iterator methods

* all: rename Iteratee.NewIteratorWith -> NewIterator

* ethdb: fix review concerns

cmd/utils/cmd.go

@@ -301,7 +301,7 @@ func ExportPreimages(db ethdb.Database, fn string) error {
 		defer writer.(*gzip.Writer).Close()
 	}
 	// Iterate over the preimages and export them
-	it := db.NewIteratorWithPrefix([]byte("secure-key-"))
+	it := db.NewIterator([]byte("secure-key-"), nil)
 	defer it.Release()
 
 	for it.Next() {