fix(ecs): get rid of EFS casing warnings (#19681)

About a year ago, ECS TaskDefinition handler changed the casing of some
EFS-related properties:

* `EfsVolumeConfiguration` -> `EFSVolumeConfiguration`
* `FileSystemId` -> `FilesystemId`

They continue to accept both casings, but emit a warning when the
deprecated casing is used. When the new casing was introduced, we
reverted to the old casing in order to not cause resource replacements.

However:

- The old casings emit warnings; when the service/task creation fails
  due to unrelated reasons, users see the warnings, interpret them as
  errors, then stop looking and come and tell us that there is a bug
  in CDK.
- Task definition replacement isn't actually a problem. Task definitions
  can be replaced for something as trivial as changing CPU count or
  memory size. Replacing them for a change that is effectively a no-op
  shouldn't matter. Yes, this will restart `Service`s based on these
  Task Definitions, but if you are only running 1 copy of the Task
  you have made the decision not to care about potential downtime of
  your service.

Maintaining the patch does not seem worth the cost/benefit ratio.

Reverts #10483, closes #15025.


----

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packages/@aws-cdk/aws-ecs/lib/base/task-definition.ts

@@ -509,7 +509,7 @@ export class TaskDefinition extends TaskDefinitionBase {
           scope: spec.dockerVolumeConfiguration.scope,
         },
         efsVolumeConfiguration: spec.efsVolumeConfiguration && {
-          fileSystemId: spec.efsVolumeConfiguration.fileSystemId,
+          filesystemId: spec.efsVolumeConfiguration.fileSystemId,
           authorizationConfig: spec.efsVolumeConfiguration.authorizationConfig,
           rootDirectory: spec.efsVolumeConfiguration.rootDirectory,
           transitEncryption: spec.efsVolumeConfiguration.transitEncryption,

packages/@aws-cdk/aws-ecs/package.json

@@ -81,6 +81,7 @@
   "devDependencies": {
     "@aws-cdk/assertions": "0.0.0",
     "@aws-cdk/aws-s3-deployment": "0.0.0",
+    "@aws-cdk/aws-efs": "0.0.0",
     "@aws-cdk/cdk-build-tools": "0.0.0",
     "@aws-cdk/cdk-integ-tools": "0.0.0",
     "@aws-cdk/cfn2ts": "0.0.0",

packages/@aws-cdk/aws-ecs/test/ec2/ec2-task-definition.test.ts

@@ -1154,8 +1154,8 @@ describe('ec2 task definition', () => {
         Family: 'Ec2TaskDef',
         Volumes: [{
           Name: 'scratch',
-          EfsVolumeConfiguration: {
-            FileSystemId: 'local',
+          EFSVolumeConfiguration: {
+            FilesystemId: 'local',
           },
         }],
       });