#12794 - The same event participant should not be allowed to be selected

[carina29]

Fixes #12794

[sormas-vitagroup]

SonarCloud analysis: https://sonarcloud.io/dashboard?id=SORMAS-Project&pullRequest=12843

[sormas-vitagroup]

SonarCloud analysis: https://sonarcloud.io/dashboard?id=SORMAS-Project&pullRequest=12843

[sormas-vitagroup]

SonarCloud analysis: https://sonarcloud.io/dashboard?id=SORMAS-Project&pullRequest=12843

[sormas-vitagroup]

SonarCloud analysis: https://sonarcloud.io/dashboard?id=SORMAS-Project&pullRequest=12843

[sormas-vitagroup]

SonarCloud analysis: https://sonarcloud.io/dashboard?id=SORMAS-Project&pullRequest=12843

[MateStrysewske]

Found an incorrect workflow:

• Create an event with a specific disease (e.g. COVID-19), and create an event participant for that event
• Create a case of the same disease for the same person
• Go to the "Events" section of the case and try to link the case to the created event

Behaviour: Warning message that this case has already been linked to the event appears, which is not true as only the person has been added to the event, but not their case.

Expected Behaviour: Linking the case to the event is successful, but of course no new event participant is created, but the existing person in the event is used instead. If the user tries again to link the same event (after successfully linking the case once), the warning message is displayed.

[sormas-vitagroup]

SonarCloud analysis: https://sonarcloud.io/dashboard?id=SORMAS-Project&pullRequest=12843

[sormas-vitagroup]

SonarCloud analysis: https://sonarcloud.io/dashboard?id=SORMAS-Project&pullRequest=12843