ECS Service Discovery registering SRV record with only one value to Route53

### Summary
ECS Service Discovery doesn't create multiple values in SRV record for ECS service task

### Description
There is possible to map only one value in SRV record for ECS Service Task and only one value will be registered in Service Discovery (Route53). Seems True for Bridge and AWSVPC modes

### Expected Behavior
Enable multiple values in SRV record per ECS service tasks.

#dig -t srv servicename.localdns
;; ANSWER SECTION:
servicename.localdns. 60 IN SRV 1 1 5000 11-922-33-83ab-444.servicename.localdns.
servicename.localdns. 60 IN SRV 20 20 5020 22-222-33-83-444.servicename.localdns.
servicename.localdns. 60 IN SRV 30 30 5030 33-33-33-83-444.servicename.localdns.

### Observed Behavior
Only one value for SRV record registered by Service Discovery per Service task

### Environment Details
ECS, agent ver. 1.28.1

### Supporting Log Snippets

a) From Service-Discovery-Considerations doc page:
...If you are using the Amazon ECS console, the workflow creates one service discovery service per ECS service. It maps all of the task IP addresses as A records, or task IP addresses and port as SRV records...
b) Route53 supports RFC2782 https://tools.ietf.org/html/rfc2782 and it is possible to create multiple values in SRV record.

Start with the Service-Discovery-Considerations documentation and the linked RFC2782 reference, then review the reported dig output for bridge and AWSVPC modes. Done means ECS service discovery registers multiple SRV values for a service's tasks, with the result verifiable through dig.

Written by the indexing model from the issue text.