refactor(rust): Remove top-level metadata from `ArrowSchema` #11040

Job	Run time
integration-test (ubuntu-latest)	1m 46s
check-wasm	5m 46s
integration-test (windows-latest)	5m 20s
check-features	7m 56s
test (ubuntu-latest)	3m 37s
test (windows-latest)	10m 12s
	34m 37s

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