(ecs-patterns): ScheduledFargateTask - runtime platform ignored

### Describe the bug

The runtime platform on the pattern top level is getting ignored when set, for example as LINUX ARM64.

```
const scheduledTask = new ecsPatterns.ScheduledFargateTask(this, 'ScheduledTask', {
cluster: cluster,
schedule: Schedule.expression('cron(*/1 * * * ? *)'),
subnetSelection: subnetsSelection,
scheduledFargateTaskImageOptions: {
image: ecs.ContainerImage.fromDockerImageAsset(dockerAsset),
memoryLimitMiB: 512,
cpu: 256,
command: ['python', 'manage.py'],
logDriver: new ecs.AwsLogDriver({streamPrefix: 'ScheduledTask'}),
environment: {
DEBUG: "1",
},
secrets: {
...secrets,
},
},
runtimePlatform: {
cpuArchitecture: ecs.CpuArchitecture.ARM64,
operatingSystemFamily: ecs.OperatingSystemFamily.LINUX,
},
});
```

### Expected Behavior

The task definition should have the image arch set to LINUX/ARM64

### Current Behavior

The task definition should have the image arch is not set. Therefore defaults to LINUX/X86_64 during deployment

### Reproduction Steps

```
const scheduledTask = new ecsPatterns.ScheduledFargateTask(this, 'ScheduledTask', {
cluster: cluster,
schedule: Schedule.expression('cron(*/1 * * * ? *)'),
subnetSelection: subnetsSelection,
scheduledFargateTaskImageOptions: {
image: ecs.ContainerImage.fromDockerImageAsset(dockerAsset),
memoryLimitMiB: 512,
cpu: 256,
command: ['python', 'manage.py'],
logDriver: new ecs.AwsLogDriver({streamPrefix: 'ScheduledTask'}),
environment: {
DEBUG: "1",
},
secrets: {
...secrets,
},
},
runtimePlatform: {
cpuArchitecture: ecs.CpuArchitecture.ARM64,
operatingSystemFamily: ecs.OperatingSystemFamily.LINUX,
},
});
```

### Possible Solution

_No response_

### Additional Information/Context

_No response_

### CDK CLI Version

2.100

### Framework Version

_No response_

### Node.js Version

20.8

### OS

Mac

### Language

TypeScript

### Language Version

_No response_

### Other information

_No response_

Start at the ScheduledFargateTask entry point and trace how the supplied runtimePlatform reaches the generated task definition. Reproduce the issue with the provided Linux/ARM64 configuration, then add coverage showing that the task definition preserves both settings and run the focused tests.

Written by the indexing model from the issue text.