Support logs delimiters for Service logs

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**Tell us about your request**

We would like to be able to specify a log delimiter for App runner service logs in a manner similar to what can be specified for the ECS Task Definition -> ContainerDefinitions -> LogConfiguration -> Options -> awslogs-datetime-format.

**Describe alternatives you've considered**
At this stage, we have considered using ECS as an alternative

**Additional context**
Anything else we should know?

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