Fix IDAKLU output_variables to work with extrapolation events #10625

Job	Run time
style	25s
Doctests (ubuntu-latest / Python 3.11)	3m 40s
Example notebooks (ubuntu-latest / Python 3.12)	18m 2s
Example scripts (ubuntu-latest / Python 3.12)	13m 56s
Tests (ubuntu-latest / Python 3.9)	29m 17s
Tests (ubuntu-latest / Python 3.10)	29m 38s
Tests (ubuntu-latest / Python 3.11)	26m 43s
Tests (ubuntu-latest / Python 3.12)	34m 19s
Tests (macos-12 / Python 3.9)	32m 15s
Tests (macos-12 / Python 3.10)	31m 18s
Tests (macos-12 / Python 3.11)	28m 46s
Tests (macos-12 / Python 3.12)	24m 21s
Tests (macos-14 / Python 3.9)	10m 52s
Tests (macos-14 / Python 3.10)	12m 14s
Tests (macos-14 / Python 3.11)	17m 19s
Tests (macos-14 / Python 3.12)	14m 33s
Tests (windows-latest / Python 3.9)	31m 27s
Tests (windows-latest / Python 3.10)	33m 31s
Tests (windows-latest / Python 3.11)	30m 50s
Tests (windows-latest / Python 3.12)	25m 11s
	7h 28m 37s

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