POC: combined schedulers

[jpbruinsslot]

Changes

• Removal of creation of organisational schedulers. Main impact is seen in the app.py
• Task get a specific organisation field
• Updates for endpoints

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Demo

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QA notes

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Code Checklist

• All the commits in this PR are properly PGP-signed and verified.
• This PR only contains functionality relevant to the issue.
• I have written unit tests for the changes or fixes I made.
• I have checked the documentation and made changes where necessary.
• I have performed a self-review of my code and refactored it to the best of my abilities.

• Tickets have been created for newly discovered issues.
• For any non-trivial functionality, I have added integration and/or end-to-end tests.
• I have informed others of any required .env changes files if required and changed the .env-dist accordingly.
• I have included comments in the code to elaborate on what is not self-evident from the code itself, including references to issues and discussions online, or implicit behavior of an interface.

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Checklist for code reviewers:

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Checklist for QA:

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