fix: change SliceName to slice-name because of replacement in the backend

[gatici]

Description

omec-project/webconsole#244 introduces a name change in the backend which is NetworkSlice to network-slice. Another change is done in the backend: omec-project/webconsole#248 to fix the DB operation. The change in the Slice name also broke the front-end and name does not appear in the slices and device groups does not appear in the subscribers.
This patch fixes the issue.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code.
• I have made corresponding changes to the documentation.
• I have added tests that validate the behaviour of the software.
• I validated that new and existing unit tests pass locally with my changes.
• Any dependent changes have been merged and published in downstream modules.