Remove `FieldSet.compute_on_defer` #667

Job	Run time
py3.13 \| macos \| unit tests	6m 39s
mypy	3m 27s
py3.13 \| ubuntu \| unit tests	9m 9s
py3.13 \| macos \| integration tests	17m 42s
py3.13 \| windows \| unit tests	12m 59s
py3.13 \| ubuntu \| integration tests	14m 24s
py3.10 \| ubuntu \| unit tests	10m 12s
py3.13 \| windows \| integration tests	24m 26s
py3.11 \| ubuntu \| unit tests	9m 56s
py3.10 \| ubuntu \| integration tests	14m 26s
py3.12 \| ubuntu \| unit tests	9m 51s
merge-test-artifacts	5s
	2h 13m 16s

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