[Enhancement] Let each agent node have its specific nametag/executors in EC2

[peterzhuamazon]

As of now all of the agent node in ec2 is consuming the same name tag.

We want to have different name tags based on label such like this:

This is controlled in GUI by this:

Also, the Single-Host and Docker-Builder requires to have only 1 executor.
While the Docker-Host one can up to 6 or 8.

Will change those as well here.

Thanks.

[peterzhuamazon]

There used to be a case where jenkins crashed and does not record that agent anymore but still show up in EC2 dangling for days. It is easier for us to identify the node and do cleanups.