How to set autoload from “yes” to “no” _transient_wp_core_block_css_files

Don’t bother messing the with autoload on the transient. If you’re truly not using blocks at all, just unhook the function that creates the transient and uses it to register the style handles:

remove_action( 'init', 'register_core_block_style_handles', 9 );

Just be aware that if you do use blocks, their stylesheets will not load until you let WordPress create the transient again.