Lower paramiko log level

Current situation

If DEBUG_LEVEL is set to DEBUG, Paramiko's log level is set to DEBUG too, which fills logs with distracting information.

Desired outcome

If DEBUG_LEVEL is set to DEBUG, Paramiko's log level should stay at INFO level. If SSHCHANNEL_DEBUG_LEVEL is set to DEBUG (or NOTSET), then Paramiko's log level should be set to DEBUG (or NOTSET) too, so that in cases this is needed the logs are not lost