The `wp_new_comment()`, `wp_update_comment()`, and `wp_filter_comment()` functions already normalize the `user_ID` parameter internally to `user_id`, which matches the database field name.
This commit aims to bring some consistency when passing the parameter in core.
The corresponding `$user_ID` variable is also renamed to `$user_id` to match the other variables when not referring to the `$user_ID` global, which has an exception in the WordPress coding standards.
Follow-up to [8543], [8720], [12267], [12300], [26491], [28915], [28922], [34799], [49303].
See #55647, #56244.
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git-svn-id: http://core.svn.wordpress.org/trunk@53288 1a063a9b-81f0-0310-95a4-ce76da25c4cd