Update MySQL Global Stats datasource to read config from my.cnf

Or, you could not add SSH overhead and just use a query :).

MariaDB [(none)]> show variables like '%conn%';
+-----------------------------------------------+-----------------+
| Variable_name                                 | Value           |
+-----------------------------------------------+-----------------+
| character_set_connection                      | utf8            |
| collation_connection                          | utf8_general_ci |
| connect_timeout                               | 10              |
| default_master_connection                     |                 |
| extra_max_connections                         | 1               |
| init_connect                                  |                 |
| max_connect_errors                            | 100             |
| max_connections                               | 151             |
| max_user_connections                          | 0               |
| performance_schema_session_connect_attrs_size | -1              |
+-----------------------------------------------+-----------------+
10 rows in set (0.00 sec)

Confirmed via same user with GRANT USAGE as normally required for "show global status" results.