Enable Jetpack Shortlinks for custom post types

[dd32]

Jetpack shortlinks are enabled by default for WordCamps, but are only enabled for the posts/pages post types.

We should enable them for custom post types too.

As mentioned on slack: https://wordpress.slack.com/archives/C08M59V3P/p1726512188669839

Enabling it for any public post types is straight forward: https://jetpack.com/support/wp-me-shortlinks/#:~:text=from%20WordPress.com.-,Enable%20shortlinks%20for%20Custom%20Post%C2%A0Types,-By%20default%2C%20WP