Describe the bug
workspaces are still accessible via their URL after they are deleted
See also #4307 as this functionality may be required

Steps to reproduce

1. Create a workspace
2. copy the url
3. delete the workspace
4. re-visit the url

Azure TRE release version (e.g. v0.14.0 or main):
main
Deployed Azure TRE components - click the (i) in the UI:

Azure TRE
UI Version:
0.8.17
API Version:
0.25.2