[candidate_parameters] Fix DB select with iterator_to_array

[CamilleBeau]

Brief summary of changes

This PR wraps the $db->pselect() call with iterator_to_array so that it can be processed with .map in DiagnosisEvolution.js. This is necessary following the change in #9334

• Have you updated related documentation?

Testing instructions (if applicable)

1. Open the candidate parameters module for any participant and go to the Diagnosis Evolution tab
2. Make sure there are no errors

Link(s) to related issue(s)

• Resolves [candidate_parameters] Error related to diagnosisEvolution #9711

[driusan]

@CamilleBeau did you try this with a candidate that returns 0 rows to ensure it's encoded as [] and not {}?

[CamilleBeau]

@CamilleBeau did you try this with a candidate that returns 0 rows to ensure it's encoded as [] and not {}?

Yes I tried with both a participant with and without data