TEST-#7686: Fix comparisons in caster tests to check the backend instead of type #17200

Job	Run time
python-filter	3s
execution-filter	7s
lint (mypy)	1m 55s
lint (flake8)	17s
Test API, headers and no-engine mode	2m 59s
test-clean-install-ubuntu	6m 5s
test-clean-install-windows	2m 29s
test-internals	14m 10s
test-asv-benchmarks	20s
Test BaseOnPython execution, Python 3.9"	27m 50s
test experimental	12m 25s
test-spreadsheet (engine dask, python 3.9)	4m 0s
test-ubuntu-sanity (engine ray, python 3.9)	31m 43s
test-native-dataframe-interoperability python 3.9)	8m 10s
test-spreadsheet (engine ray, python 3.9)	3m 35s
test-ubuntu-sanity (engine unidist, python 3.9)	27m 9s
test-windows-sanity (engine ray, python 3.9)	32m 29s
test-windows-sanity (engine dask, python 3.9)	45m 20s
test-windows-sanity (engine unidist, python 3.9)	22m 28s
test-ubuntu-sanity (engine dask, python 3.9)	51m 39s
test-ubuntu (engine python, python 3.9, group_1)	35m 48s
test-ubuntu (engine native, python 3.9, group_1)	26m 50s
test-windows (engine native, python 3.9, group_1)	42m 34s
test-windows (engine python, python 3.9, group_1)	49m 23s
test-ubuntu (engine unidist ${{ matrix.unidist-backend }}, python ${{ matrix.python-version }})	0s
merge-coverage-artifacts	5s
upload-coverage	27s
	7h 30m 20s

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