Split out ARM64 test-fast from matrix, make nonrequired #5524

Job	Run time
test	10m 41s
pure-rust-build	2m 2s
test-journey	4m 5s
cargo-deny	26s
cargo-deny-advisories	26s
check-blocking	4s
check-packetline (ubuntu-latest)	6s
lint	3m 43s
test-32bit (i386)	5m 56s
test-32bit (arm32v7)	4m 3s
test-fast (windows-latest)	19m 20s
test-fast (macos-latest)	5m 42s
test-fast-arm	5m 54s
test-fast (ubuntu-latest)	6m 37s
test-fixtures-windows	14m 0s
WebAssembly (wasm32-unknown-unknown)	1m 10s
WebAssembly (wasm32-wasip1)	42s
Tests pass	1s
	1h 24m 58s

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