Change test for valid transition distribution from ide model

[lenaploetzke]

Motivation / Current Behaviour

Currently, the unused TransitionDistribution S->E is tested for validity, which can cause unexpected errors.

Enhancement description

Remove Test of this TransitionDistribution.

Additional context

Code can be copied from #771: cpp/models/ide_secir/parameters.h

Checklist

• Attached labels, especially loc:: or model:: labels.
• Linked to project