This PR adds new optional config to cloud-instance for letting cloud-instance.sh ec2 launch search for an instance type across multiple subnets for an available instance. Example of the new config:

EC2_SUBNET_VARS=("EC2_SUBNET_ID_1" "EC2_SUBNET_ID_2")
EC2_SUBNET_ID_1=subnet-12345678901234567
EC2_SUBNET_ID_2=subnet-12345678901234568

So if you were looking for a g6e.12xlarge, it would first look in subnet-12345678901234567, if an available instance wasn't found there, it would then look in subnet-12345678901234568. If still no instance was found it would fail.

Checklist:

• Commit Message Formatting: Commit titles and messages follow guidelines in the
  conventional commits.
• Changelog updated with breaking and/or notable changes for the next minor release.
• Documentation has been updated, if necessary.
• Unit tests have been added, if necessary.
• Functional tests have been added, if necessary.
• E2E Workflow tests have been added, if necessary.