[BUG] swagger is using field name dataflow in an inconsistent case with azure portal

### API Spec link

https://github.com/Azure/azure-rest-api-specs/blob/main/specification/datafactory/resource-manager/Microsoft.DataFactory/stable/2018-06-01/entityTypes/Pipeline.json#L8484

### API Spec version

2018-06-01

### Describe the bug

Swagger defined the field name as `dataFlow` while azure portal is using `dataflow`, which would cause incompatibility among different platforms.


### Expected behavior

Service should unify the field name instead of using multiple parallel field names for one property.

### Actual behavior

Because of this inconsistency, SDK generated by swagger can only read dataflow by field name `dataFlow`, not `dataflow` from pipeline created by rest api or azure portal.

### Reproduction Steps

1. create a pipeline with dataflow activity with field name `dataflow` by [rest api](https://learn.microsoft.com/en-us/rest/api/datafactory/pipelines/create-or-update?view=rest-datafactory-2018-06-01&tabs=HTTP#code-try-0) or create it by azure portal.

2. get the pipeline by rest api, and it's able to read `dataflow` property with field name `dataflow`.

3. yet if get it though SDK, it failed to read dataflow since sdk can only read the field name `dataFlow`.

### Environment

_No response_

Open specification/datafactory/resource-manager/Microsoft.DataFactory/stable/2018-06-01/entityTypes/Pipeline.json at the linked line and compare the declared field name with the REST API and Azure portal behavior described in the issue. Update the API specification so the property uses one consistent casing, then verify that the generated SDK can read pipelines returned with the service's field name.

Written by the indexing model from the issue text.