Don't leave empty arrays in the service control target

[karwosts]

Proposed change

I think we have a regression due to #18772, now when switching services we populate empty arrays in the target field.

target:
  entity_id:
    - alarm_control_panel.manual_alarm
  device_id: []
  area_id: []

Some backend service validators don't like this and will throw an error, e.g. services that don't accept areas will fail this target with a confusing error message. User must remove these manually from yaml to fix it.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (thank you!)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Example configuration

Additional information

• This PR fixes or closes issue: fixes "homeassistant.update_entity": cannot call from Dev tools -> Services with default code #18979
• This PR is related to issue or discussion:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io