[ECS] [Fargate][Bug]: target group ignores custom port

An annoying bug, when setting up a service there is an option for a new target group which defaults to port 80. Entering a different value here doesn't translate to the value being used which continues to be 80.

A workaround is to create the target group and ELB in VPC prior to creating the service and attaching at that point.

Start by reproducing the ECS/Fargate service setup described in the issue: create a target group with a custom port and attach it during service creation. Compare the configured port with the port used by the resulting target group attachment; done means the entered custom port is retained instead of defaulting to 80.

Written by the indexing model from the issue text.