Add Verbose Filters to Counting Existing Instances

[pyieh]

In the case of when there are multiple Jenkins in the same AWS account sharing the same URL but in different VPCs (e.g. when migrating from 1 Kubernetes cluster to another)
Similar (but not exactly) to : #310

When counting the number of existing instances to determine if there's capacity to create new instances for a given SlaveTemplate, there is a bug where the EC2 plugin will count EC2 instances regardless of different characteristics than the ones configured on the given SlaveTemplate: notably security group, subnet, VPC, and IAM roles. Instances with different characteristics than those on the given SlaveTemplate shouldn't be counted as it could have different network permissions, be unreachable due to different subnets, etc.

Fix is to add more verbose filters when making the AWS request for instance count. The following filters were added: security group, subnet, IAM role, VPC.

Note VPC is only added when counting all instances and uses the given SlaveTemplate's configured subnet to get the respective VPC.

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