CLOUDSTACK-4911 [Mixed Hypervisor] VM Status is marked as alive when exit status of ping command is not available within command timeout

Supplementing the fix/commit 748315620bbbc472652e38df960d136beee4882e
While remote executing commands through ssh, wait for channel condition of EXIT_STATUS.

Signed-off-by: Sateesh Chodapuneedi <sateesh@apache.org>