CLOUDSTACK-6047: Fix timeout issue when try to execute aggregated commands

Add executeInVR() with timeout interface to VirtualRouterDeployer

AggregationControlCommand with Action.Finish may take longer than normal command
since it would execute all the commands in one execution, and it may result in
SSH timeout for SshHelper or other mechanism communicate with VR.

Introduce an new executeInVR() interface with added timeout period for waiting
FinishAggregationCommand to complete execution.