Remove unused ArrayRef::is_arrow #5616

Job	Run time
check-java-publish-build (x86_64-unknown-linux-gnu, runs-on=29782808730/runner=amd64-medium/image...	1m 22s
Rust publish dry-run	22s
Python (wheel build)	5m 55s
check-java-publish-build (aarch64-unknown-linux-gnu, runs-on=29782808730/runner=arm64-medium/imag...	1m 59s
Compat check / compat-test	3m 27s
	13m 5s

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