Remove doubled fmt check from CI

Examples' format is checked in `check-fmt` job, so can be skipped in
`rust_example.sh`.

Author: findepi

ci/scripts/rust_example.sh

@@ -19,7 +19,6 @@
 
 set -ex
 cd datafusion-examples/examples/
-cargo fmt --all -- --check
 cargo check --examples
 
 files=$(ls .)