Fix precomputed on hold status should show spent time and run button should be disabled

[slax57]

Problem

When a Precomputation is in status ON_HOLD:

• It doesn't show the spent time (which would be useful to guess if the job has failed or is still pending)
• The Run button is still active, but if you click on it it raises an error

Solution

• Also display the spent time with status ON_HOLD
• Disable the run button with status ON_HOLD