Comments: Introduce `wp_update_comment_type_batch_size` filter for the comment...

Comments: Introduce `wp_update_comment_type_batch_size` filter for the comment batch size in `_wp_batch_update_comment_type()`.

Follow-up to [47597].

Props dchymko.
Fixes #50513. See #49236.
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git-svn-id: https://core.svn.wordpress.org/trunk@47994 1a063a9b-81f0-0310-95a4-ce76da25c4cd