[BUG] Same input is send on every dispatched workflow - Bulk dispatch workflow activity

## Description
If we try to use the Bulk Dispatch Workflows activity with more than one item while having the mass-transit disabled, the same input will be sent to every dispatched workflow. This is reproducible every time and it always take the last item values.

## Steps to Reproduce
- Import the workflow defintions
- Publish the worklows
- Run the parent workflow using the Run button (not a requirement but easy to do)

3. **Attachments**:
[workflow-definitions (7).zip](https://github.com/elsa-workflows/elsa-core/files/15020991/workflow-definitions.7.zip)

4. **Reproduction Rate**: Indicate how often the bug occurs when following these steps (e.g., "every time", "intermittently: about 50% of the time").
Every time.

6. **Video/Screenshots**: Sometimes, complex behaviors are better shown than described. If you think a video or screenshots would help clarify the issue, please include them.
No video/screenshot.

8. **Additional Configuration**:
Mass transit has to be disabled.

## Expected Behavior
Each item values should be sent to one workflow only. First item to first workflow, second item to second workflow,...

## Actual Behavior
The last item values are sent to every workflow.

## Screenshots

## Environment
- Elsa: 3.1.1
- Windows
- Edge

## Log Output
No log.

## Troubleshooting Attempts
The background provider is used, which relies on MediatR. The sending part seems ok, but in the DispatchedWorkflowHandler we received the same value every time, while we should have received different values (based on the Items array).

## Additional Context
No additional info.

## Related Issues
No related issue.