How concat two sql query in a single result
I assume you can join the queries one way or another (I see no correlation so I'll assume a cross join):

SELECT ...
FROM (
    SELECT ticketing_ticket.email,
    CONCAT(
          TIMESTAMPDIFF(day,date_create,date_close) , ' jours ',
          MOD( TIMESTAMPDIFF(hour,date_create,date_close), 24), ' heures ',
          MOD( TIMESTAMPDIFF(minute,date_create,date_close), 60), ' miinutes '
    ) AS 'temps de traitement '
    FROM ticketing_ticket 
    WHERE DATE(date_close) = CURDATE()
) AS X
CROSS JOIN (
    SELECT GROUP_CONCAT(T2.label SEPARATOR ';') AS 'Domaines'
    FROM (
        SELECT @r AS _id,
             (SELECT @r := id_parent 
              FROM ticketing_category 
              WHERE id_category = _id) AS parent_id,
              @l := @l + 1 AS lvl
        FROM (
            SELECT @r := 38, @l := 0) vars, ticketing_category m
        WHERE @r &lt;&gt; 0
    ) T1
    JOIN ticketing_category T2
        ON T1._id = T2.id_category
) y;


Mixing old "," joins and ANSI joins makes it difficult to read the code. so I'll suggest that you remove the ";" joins:

SELECT ...
FROM (
    SELECT ticketing_ticket.email,
    CONCAT(
          TIMESTAMPDIFF(day,date_create,date_close) , ' jours ',
          MOD( TIMESTAMPDIFF(hour,date_create,date_close), 24), ' heures ',
          MOD( TIMESTAMPDIFF(minute,date_create,date_close), 60), ' miinutes '
    ) AS 'temps de traitement '
    FROM ticketing_ticket 
    WHERE DATE(date_close) = CURDATE()
) AS X
CROSS JOIN (
    SELECT GROUP_CONCAT(T2.label SEPARATOR ';') AS 'Domaines'
    FROM (
        SELECT @r AS _id,
             (SELECT @r := id_parent 
              FROM ticketing_category 
              WHERE id_category = _id) AS parent_id,
              @l := @l + 1 AS lvl
        FROM ( SELECT @r := 38, @l := 0) vars
        CROSS JOIN ticketing_category m
        WHERE @r &lt;&gt; 0
    ) T1
    JOIN ticketing_category T2
        ON T1._id = T2.id_category
) y;