docs: remove suffix -race from usage documentation

[sanadhis]

Remove this suffix -race from usage doc as the binary apparently doesn't have this -race suffix.

Test from docker image altinity/clickhouse-backup:2.4.17:

ca0659cd2951:/# ls -lah /bin | grep clickhouse
-rwxr-xr-x    1 root     root       46.8M Jan  9 16:13 clickhouse-backup
ca0659cd2951:/# which clickhouse

Note: this is my first time opening PR to this repository, so appreciate any feedback!

[Slach]

Nice catch, thank you so much for contribution