Remove deferred loading of FieldSets #668

Job	Run time
mypy	4m 3s
py3.13 \| macos \| integration tests	17m 48s
py3.13 \| macos \| unit tests	8m 2s
py3.13 \| ubuntu \| integration tests	16m 32s
py3.13 \| windows \| integration tests	28m 4s
py3.13 \| ubuntu \| unit tests	9m 22s
py3.10 \| ubuntu \| integration tests	16m 44s
py3.13 \| windows \| unit tests	11m 25s
py3.10 \| ubuntu \| unit tests	10m 7s
py3.11 \| ubuntu \| unit tests	9m 54s
py3.12 \| ubuntu \| unit tests	9m 36s
merge-test-artifacts	0s
	2h 21m 37s

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