usage_time in session.details() returns None for ibm_cloud channel

[LenaPer]

Describe the bug
Comparing the sessions details between the ibm_cloud and the ibm_quantum channels, I saw that the usage_time was always None for cloud vs it always showed an actual number for the platform

Steps to reproduce

• run a session via cloud
• check session.details()['usage_time']

Expected behavior
it returns the usage time of the session

Suggested solutions

Additional Information

• qiskit-ibm-runtime version: 0.29.0
• Python version: 3.11.3
• Operating system: macOS

[kt474]

This would have to be fixed on the server side - usage is not yet supported on the cloud channel #1567 (comment)