MDEV-22722 Assertion "inited==NONE" failed in handler::ha_index_init on the slave during UPDATE

Add missing call for handler->prepare_for_insert() in Rows_log_event::do_apply_event

mysql-test/main/long_unique_bugs_replication.result

+include/master-slave.inc
+[connection master]
+create table t1 (i1 int, a1 text, unique key i1 (a1)) engine=myisam;
+insert into t1 values (1,1);
+insert into t1 values (2,2);
+update t1 set a1 = 'd' limit 1;
+update t1 set a1 = 'd2' where i1= 2;
+connection slave;
+connection slave;
+connection master;
+drop table t1;
+include/rpl_end.inc

mysql-test/main/long_unique_bugs_replication.test

+#
+# Long unique bugs related to master slave replication
+#
+
+#
+# MDEV-22722 Assertion "inited==NONE" failed in handler::ha_index_init on the slave during UPDATE
+#
+
+--source include/have_binlog_format_row.inc
+--source include/master-slave.inc
+
+create table t1 (i1 int, a1 text, unique key i1 (a1)) engine=myisam;
+insert into t1 values (1,1);
+insert into t1 values (2,2);
+update t1 set a1 = 'd' limit 1;
+update t1 set a1 = 'd2' where i1= 2;
+
+sync_slave_with_master;
+connection slave;
+
+connection master;
+drop table t1;
+
+--source include/rpl_end.inc

sql/log_event_server.cc

@@ -5570,6 +5570,8 @@ int Rows_log_event::do_apply_event(rpl_group_info *rgi)
   {
     master_had_triggers= table->master_had_triggers;
     bool transactional_table= table->file->has_transactions_and_rollback();
+    table->file->prepare_for_insert(get_genral_type_code() != WRITE_ROWS_EVENT);
+
     /*
       table == NULL means that this table should not be replicated
       (this was set up by Table_map_log_event::do_apply_event()