Fix IDAKLU output_variables to work with extrapolation events #10635

Job	Run time
style	25s
Example notebooks (ubuntu-latest / Python 3.12)	18m 58s
Example scripts (ubuntu-latest / Python 3.12)	14m 26s
Doctests (ubuntu-latest / Python 3.11)	3m 42s
Tests (ubuntu-latest / Python 3.9)	30m 48s
Tests (ubuntu-latest / Python 3.10)	30m 9s
Tests (ubuntu-latest / Python 3.11)	27m 18s
Tests (ubuntu-latest / Python 3.12)	34m 34s
Tests (macos-12 / Python 3.9)	21m 7s
Tests (macos-12 / Python 3.10)	25m 31s
Tests (macos-12 / Python 3.11)	22m 54s
Tests (macos-12 / Python 3.12)	24m 1s
Tests (macos-14 / Python 3.9)	14m 22s
Tests (macos-14 / Python 3.10)	11m 55s
Tests (macos-14 / Python 3.11)	18m 21s
Tests (macos-14 / Python 3.12)	11m 17s
Tests (windows-latest / Python 3.9)	32m 9s
Tests (windows-latest / Python 3.10)	32m 29s
Tests (windows-latest / Python 3.11)	30m 7s
Tests (windows-latest / Python 3.12)	27m 23s
	7h 11m 56s

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