Log rustfmt output if it fails; also do not check that rustfmt exists
Log rustfmt output if it fails; also do not check that rustfmt exists

Worst case is that the logs will have multiple errors caused by missing
rustfmt, so checking separately that rustfmt exists is unnecessary.

eminence/cargo,tsurai/cargo,rust-lang/cargo,tshepang/cargo,tshepang/cargo,vojtechkral/cargo,tsurai/cargo,nipunn1313/cargo,eminence/cargo,tshepang/cargo,tsurai/cargo,nipunn1313/cargo,rust-lang/cargo,tshepang/cargo,eminence/cargo,vojtechkral/cargo,rustyhorde/cargo,tsurai/cargo,rust-lang/cargo,rustyhorde/cargo,rustyhorde/cargo,rustyhorde/cargo,eminence/cargo,vojtechkral/cargo,nipunn1313/cargo,nipunn1313/cargo,vojtechkral/cargo,rust-lang/cargo,tsurai/cargo