Remove `netcdf_engine` from Field and FieldSet #697

Job	Run time
mypy	49s
py3.13 \| macos \| integration tests	48s
py3.13 \| macos \| unit tests	1s
py3.13 \| ubuntu \| integration tests	47s
py3.13 \| ubuntu \| unit tests	47s
py3.13 \| windows \| integration tests	44s
py3.13 \| windows \| unit tests	43s
py3.10 \| ubuntu \| integration tests	47s
py3.10 \| ubuntu \| unit tests	49s
py3.11 \| ubuntu \| unit tests	47s
py3.12 \| ubuntu \| unit tests	47s
merge-test-artifacts	1s
	7m 50s

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