Remove polyfill dependencies

[mkaz]

Description

With the merging of WordPress/gutenberg#35038
the wp-polyfill is no longer a required dependency for the blocks.

[ryanwelcher]

Looks great! The only thing worth mentioning is that the blocks with a build process will most likely have wp-polyfill added back in via this setting in the @wordpress/scripts - https://github.com/WordPress/gutenberg/blob/trunk/packages/scripts/config/webpack.config.js#L250

[mkaz]

So, I think we can adjust this by adding WP_NO_EXTERNALS=true in front of the wp-script commands.

What do you think, should we do this by default for create-block script?

[mkaz]

Actually, I'm wrong about the WP_NO_EXTERNALS that would prevent the assets from being created at all.

I created an issue on Gutenberg repo to discuss: WordPress/gutenberg#35410

[mkaz]

With the merge of WordPress/gutenberg#35436 we can remove here.