<?php

add_filter( 'get_user_metadata', function( $meta_value, $user_id, $meta_key ) {
    preg_match( '/^edit_(.*)_per_page$/', $meta_key, $matches );
    if ( is_array( $matches ) && ! empty( $matches[1] ) ) {
        global $wpdb;
        $per_page = $wpdb->get_var( $wpdb->prepare( "SELECT meta_value FROM $wpdb->usermeta WHERE meta_key = %s AND user_id = %d", $meta_key, $user_id ) );
        if ( ! $per_page ) {
            $meta_value = 100;
        }
    }
    return $meta_value;
}, 10, 3 );