check-format-commit: call fewer unneeded processes

check-format-commit: call fewer unneeded processes

`wc` does not output a file name if the input is stdin.

`awk` reads its file argument; there's no need for `cat`.

`sort -u` outputs unique lines. It should be supported on all platforms,
as it's specified by POSIX.

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/25562)