Remove unsafe from unconditionally safe subgroup ops #544

Job	Run time
Android (ubuntu-24.04, aarch64-linux-android)	8m 24s
Test (ubuntu-24.04)	8m 5s
Difftest (windows-2022)	10m 31s
Test (windows-2022)	10m 33s
Lint	6m 24s
Test (macOS-latest)	9m 39s
Difftest (ubuntu-24.04)	9m 3s
Difftest (macOS-latest)	8m 34s
Compiletest (windows-2022)	4m 21s
Compiletest (ubuntu-24.04)	4m 12s
Compiletest (macOS-latest)	4m 37s
cargo-deny	54s
test_success	2s
	1h 25m 19s

Provide feedback