[CPDLP-1913] Restrict participants endpoint fields

This endpoint is currently timing out in production for certain
providers. One possible way to speed it up is by reducing the amount of
columns returned to only the necessary ones.

app/services/api/v1/ecf/participants_query.rb

@@ -24,7 +24,19 @@ def induction_records
                      },
                    )
 
+          necessary_fields = %i[
+            induction_programme_id
+            induction_status
+            mentor_profile_id
+            participant_profile_id
+            preferred_identity_id
+            schedule_id
+            training_status
+            updated_at
+          ]
+
           scope = InductionRecord
+                    .select(*necessary_fields)
                     .references(participant_profile: %i[participant_identity])
                     .includes(
                       :preferred_identity,