fix(ecs): secretToken required but declared as optional (#21745)

`token` is no longer a valid option in v2, so `secretToken` is required by virtue of needing to provide at least one of `token` or `secretToken`

Removed test which checks for error because `secretToken` is now required so we cannot check for error, even with `testDeprecated` to my knowledge

fixes #21744 

----

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*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: peterwoodworth

packages/@aws-cdk/aws-ecs/README.md

@@ -868,13 +868,15 @@ taskDefinition.addContainer('TheContainer', {
 ### splunk Log Driver
 
 ```ts
+declare const secret: secretsmanager.Secret;
+
 // Create a Task Definition for the container to start
 const taskDefinition = new ecs.Ec2TaskDefinition(this, 'TaskDef');
 taskDefinition.addContainer('TheContainer', {
   image: ecs.ContainerImage.fromRegistry('example-image'),
   memoryLimitMiB: 256,
   logging: ecs.LogDrivers.splunk({
-    token: SecretValue.secretsManager('my-splunk-token'),
+    secretToken: secret,
     url: 'my-splunk-url',
   }),
 });

packages/@aws-cdk/aws-ecs/lib/log-drivers/splunk-log-driver.ts

@@ -37,11 +37,8 @@ export interface SplunkLogDriverProps extends BaseLogDriverProps {
    *
    * The splunk-token is added to the SecretOptions property of the Log Driver Configuration. So the secret value will not be
    * resolved or viewable as plain text.
-   *
-   * Please provide at least one of `token` or `secretToken`.
-   * @default - If secret token is not provided, then the value provided in `token` will be used.
    */
-  readonly secretToken?: Secret;
+  readonly secretToken: Secret;
 
   /**
    * Path to your Splunk Enterprise, self-service Splunk Cloud instance, or Splunk

packages/@aws-cdk/aws-ecs/test/splunk-log-driver.test.ts

@@ -209,16 +209,4 @@ describe('splunk log driver', () => {
       ],
     });
   });
-
-  test('throws when neither token nor secret token are provided', () => {
-    expect(() => {
-      td.addContainer('Container', {
-        image,
-        logging: ecs.LogDrivers.splunk({
-          url: 'my-splunk-url',
-        }),
-        memoryLimitMiB: 128,
-      });
-    }).toThrow('Please provide either token or secretToken.');
-  });
 });