Rights basis end dates (and potentially start dates) are overwritten

[helrond]

Describe the bug

Rights basis end dates appear to be overwritten, probably by rights calculation logic, which overwrites "open" dates with hardcoded dates. This is not cool.

To reproduce

Look at https://aurora.dev.rockarch.org/app/rights/1545/

Expected behavior

Basis dates should not be overwritten, only act dates should be impacted by rights date calculations.