Docs Formatting: Backtick-escape inline code for all dynamic hook docs in wp-includes/meta.php.

Affects DocBlocks for the following hooks:
* `add_{$meta_type}_metadata`
* `add_{$meta_type}_meta`
* `added_{$meta_type}_meta`
* `update_{$meta_type}_metadata`
* `update_{$meta_type}_meta`
* `updated_{$meta_type}_meta`
* `delete_{$meta_type}_metadata`
* `delete_{$meta_type}_meta`
* `deleted_{$meta_type}_meta`
* `get_{$meta_type}_metadata`
* `delete_{$meta_type}meta`
* `deleted_{$meta_type}meta`
* `sanitize_{$meta_type}_meta_{$meta_key}`

See #30552.


git-svn-id: https://develop.svn.wordpress.org/trunk@30655 602fd350-edb4-49c9-b593-d223f7449a82