fix(mysql): hide password when logging DSN

[ilyam8]

Fixes: netdata/netdata#13770

Note: the password is not hidden in debug messages which don't get into error.log

Before

[ DEBUG ] build[manager] build.go:303 building mysql[local] job, config: map[__provider__:file reader __source__:/opt/netdata/usr/lib/netdata/conf.d/go.d/mysql.conf autodetection_retry:0 dsn:root:password@tcp(127.0.0.1:3306)/ module:mysql name:local priority:70000 update_every:1]
[ DEBUG ] mysql[local] mysql.go:111 using DSN [root:password@tcp(127.0.0.1:3306)/]
[ ERROR ] mysql[local] mysql.go:126 error on pinging the mysql database [root:password@tcp(127.0.0.1:3306)/]: dial tcp 127.0.0.1:3306: connect: connection refused

After

[ DEBUG ] build[manager] build.go:303 building mysql[local] job, config: map[__provider__:file reader __source__:/opt/netdata/usr/lib/netdata/conf.d/go.d/mysql.conf autodetection_retry:0 dsn:root:password@tcp(127.0.0.1:3306)/ module:mysql name:local priority:70000 update_every:1]
[ DEBUG ] mysql[local] mysql.go:111 using DSN [root:password@tcp(127.0.0.1:3306)/]
[ ERROR ] mysql[local] mysql.go:126 error on pinging the mysql database [root:********@tcp(127.0.0.1:3306)/]: dial tcp 127.0.0.1:3306: connect: connection refused