register_block_type_from_metadata performs unneccesary file system operations for blocks resolved from metadata registry

[kalessil]

If block metadata has been resolved via WP_Block_Metadata_Registry::get_metadata, register_block_type_from_metadata performs excessive file_exists calls, which affects block registration performance.

E.g., on Mac M4, Woo core blocks (around 170 blocks) registration in a standard wp-env-based environment drops from ±15ms to ±5ms if file_exists is skipped (which is feasible when blocks are resolved via the registry).

Trac ticket: [
](https://core.trac.wordpress.org/ticket/66416)

Use of AI Tools

AI assistance: Yes
Tool(s): Claude
Used for: adopting the optimization fixes from ​https://github.com/woocommerce/woocommerce/pull/70056 into the upstream function

@felixarntz, @gziolo, @swissspidy: looking into ​https://github.com/WordPress/wordpress-develop/pull/8129, it looks like you have decent context in the area I'm touching in this PR. Mind taking a look and sharings some feedback in case I missed something?

Here are the details from track0ticket:

 If block metadata has been resolved via WP_Block_Metadata_Registry::get_metadata, register_block_type_from_metadata performs excessive file_exists calls, which affects block registration performance.

E.g., on Mac M4, Woo core blocks (around 170 blocks) registration in a standard wp-env-based environment drops from ±15ms to ±5ms if file_exists is skipped (which is feasible when blocks are resolved via the registry). 

Perhaps @westonruter? I'm currently on vacation.