batch: EksContainerDefinition image from ECR raises RuntimeError: Cannot read property 'obtainExecutionRole' of undefined

### Describe the bug

When specifying EKS task in batch module like this:
```
container_definition = batch.EksContainerDefinition(
self,
f"foo",
image=ecs.ContainerImage.from_ecr_repository(
repository, image_tag
),
image_pull_policy=batch.ImagePullPolicy.ALWAYS,
volumes=[
batch.EksVolume.empty_dir(
name="myEmptyDirVolume",
mount_path="/mount/path",
medium=batch.EmptyDirMediumType.MEMORY,
readonly=True,
size_limit=Size.mebibytes(2048),
)
],
)

```
part `ecs.ContainerImage.from_ecr_repository` raises `RuntimeError: Cannot read property 'obtainExecutionRole' of undefined`.

CDK version: CDK_CLI_VERSION: '2.115.0', Python

### Expected Behavior

Image is successfully set

### Current Behavior

```
RuntimeError: Cannot read property 'obtainExecutionRole' of undefined
```

### Reproduction Steps

Run CDK synth with the code above

### Possible Solution

_No response_

### Additional Information/Context

_No response_

### CDK CLI Version

2.115.0 (build 58027ee)

### Framework Version

_No response_

### Node.js Version

v16.0.0

### OS

Amazon Linux

### Language

Python

### Language Version

3.11

### Other information

_No response_

Start with the EksContainerDefinition entry point and ecs.ContainerImage.from_ecr_repository, then run CDK synth with the reproduction shown in the issue. Trace the failing obtainExecutionRole call and verify that the image is successfully set without the RuntimeError.

Written by the indexing model from the issue text.