Optimize constant casts to avoid unnecessary capabilities #531

Job	Run time
Test (ubuntu-24.04)	8m 12s
Test (macOS-latest)	6m 20s
Android (ubuntu-24.04, aarch64-linux-android)	7m 52s
Test (windows-2022)	15m 8s
Compiletest (ubuntu-24.04)	7m 56s
Compiletest (windows-2022)	17m 46s
Difftest (ubuntu-24.04)	8m 23s
Lint	6m 0s
Difftest (macOS-latest)	7m 33s
cargo-deny	1m 24s
Compiletest (macOS-latest)	9m 25s
Difftest (windows-2022)	16m 28s
test_success	2s
	1h 52m 29s

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