llm-factor: migrate to `candle` #6692

Job	Run time
Lint Rust	8m 28s
Build Spin (windows-latest)	44m 3s
Build Spin static (aarch64, aarch64-unknown-linux-musl)	15m 17s
Build Spin (macos-13)	48m 32s
Build Spin Ubuntu	20m 53s
Build Spin static (amd64, x86_64-unknown-linux-musl)	6m 10s
Review new dependencies for known vulnerabilities	17s
Build Spin (macos-14)	19m 45s
Test Spin (ubuntu-22.04-4core-spin)	14m 35s
all-integration-tests	22m 59s
Test Spin (macos-14)	30m 26s
Run release build steps (ubuntu-20.04, amd64, --features openssl/vendored, target/release)	15m 2s
Run release build steps (ubuntu-20.04, aarch64, --features openssl/vendored --target aarch64-unkn...	16m 14s
Run release build steps (macos-13, amd64, target/release)	29m 36s
Run release build steps (macos-14, aarch64, target/release)	11m 56s
Run release build steps (windows-latest, amd64, .exe, target/release)	29m 33s
	5h 33m 46s

Provide feedback