Need to clean up temporarry table in select handler. Optimize the way select handler search for tables and rewrites the query.

There are number of defficiences that should be addressed in 10.4.

• Pushdown_select instance doesn't clean up the temporary table created for Select_handler
• The loop in SELECT_LEX::find_select_handler() should iterater of TABLE_LIST from next_global and not next_local. Then subquery tables' handlertons could be searched for select handler capabilities
• JOIN::optimize_inner() should be called before Select_handler::init() in JOIN::optimize(). If Select_handler::init() is called before JOIN::optimize() then processing of statements like the one is broken since Server doesn't rewrite one of outter JOINs with inner JOIN.

  select j1_key, j6_key, j11_key from j1 right join j6 on j1_key=j6_key right join j11 on j6_key = j11_key where j6_key > 0;