[BUG] ECS TaskDefinition fails to update on removal of SecretManager reference when secret key does not exist anymore

### Name of the resource

AWS::ECS::TaskDefinition

### Resource Name

_No response_

### Issue Description

When using an ECS:TaskDefinition together with a referenced AWS:SecretManager secretValueFromJson(), the stack update fails when the key does not exist, which is a bug for a scenario when some previously used secret keys are removed.

Consider the following scenario.

1. The stack defined below is deployed without any issues:

```ts

// secret holds the following JSON: {"SECRET1" : "value1", "SECRET2": "value2" }
const secret = Secret.fromSecretNameV2(this, 'secret', 'secret');

const taskDefinition = new Ec2TaskDefinition(this, 'EcsWatchdogTaskDef', {
family: 'task-def',
networkMode: NetworkMode.AWS_VPC,
});

taskDefinition.addContainer('backend', {
image: ContainerImage.fromEcrRepository(image, 'latest'),
environment: {
SECRET1: secret.secretValueFromJson('SECRET1').unsafeUnwrap(),
SECRET2: secret.secretValueFromJson('SECRET2').unsafeUnwrap(),
},
});

```

Now, the application does no longer need SECRET2 so it is removed from the SecretManager `secret` and the CDK stack definition is modified to look like below:

```ts

// secret holds the following JSON: {"SECRET1" : "value1"}
const secret = Secret.fromSecretNameV2(this, 'secret', 'secret');

const taskDefinition = new Ec2TaskDefinition(this, 'EcsWatchdogTaskDef', {
family: 'task-def',
networkMode: NetworkMode.AWS_VPC,
});

taskDefinition.addContainer('backend', {
image: ContainerImage.fromEcrRepository(image, 'latest'),
environment: {
SECRET1: secret.secretValueFromJson('SECRET1').unsafeUnwrap(),
},
});

```

`cdk diff` shows the following:

```
Stack EcsBackendService-Stack
Hold on while we create a read-only change set to get a diff with accurate replacement information (use --no-change-set to use a less accurate but faster template-only diff)
Resources
[~] AWS::ECS::TaskDefinition TaskDef TaskDef7C802DCD replace
└─ [~] ContainerDefinitions (requires replacement)
└─ @@ -104,29 +104,6 @@
[ ] }
[ ] },
[ ] {
[-] "Name": "SECRET2",
[-] "Value": {
[-] "Fn::Join": [
[-] "",
[-] [
[-] "{{resolve:secretsmanager:arn:",
[-] {
[-] "Ref": "AWS::Partition"
[-] },
[-] ":secretsmanager:",
[-] {
[-] "Ref": "AWS::Region"
[-] },
[-] ":",
[-] {
[-] "Ref": "AWS::AccountId"
[-] },
[-] ":secret:secret:SecretString:SECRET2::}}"
[-] ]
[-] ]
[-] }
[-] },

✨ Number of stacks with differences: 1
```
so all looks good, however `cdk deploy` fails with:

```
The stack named EcsBackendService-Stack failed to deploy: UPDATE_ROLLBACK_COMPLETE: Could not find a value associated with JSONKey in SecretString

```

### Expected Behavior

The stack is updated without any issues to remove the old secret reference.

### Observed Behavior

The stack named EcsBackendService-Stack failed to deploy: UPDATE_ROLLBACK_COMPLETE: Could not find a value associated with JSONKey in SecretString

### Test Cases

-

### Other Details

_No response_

No repository files, tests, or implementation entry points are identified in the issue. Start by reproducing the deployment with the two ECS task-definition examples and inspect the generated CloudFormation template and update failure; done means removing the obsolete secret reference succeeds without rollback.

Written by the indexing model from the issue text.