Docs: Remove @static notations from method DocBlocks in wp-includes/* classes.

This tag has been used in the past, but should no longer be used. Just using the `static` keyword in code is enough for PhpDocumentor on PHP5+ to recognize static variables and methods, and PhpDocumentor will mark them as static.

Props birgire.
See #42803.
Built from https://develop.svn.wordpress.org/trunk@42746


git-svn-id: http://core.svn.wordpress.org/trunk@42576 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/class-wp-user.php

@@ -180,8 +180,6 @@ class WP_User {
 	 * @since 3.3.0
 	 * @since 4.4.0 Added 'ID' as an alias of 'id' for the `$field` parameter.
 	 *
-	 * @static
-	 *
 	 * @global wpdb $wpdb WordPress database abstraction object.
 	 *
 	 * @param string $field The field to query against: 'id', 'ID', 'slug', 'email' or 'login'.