[ci] Set rust backtrace to full

Author: bonigarcia

.github/workflows/ci-rust.yml

@@ -28,4 +28,4 @@ jobs:
       name: Tests (${{ matrix.os }})
       cache-key: rust-test
       os: ${{ matrix.os }}
-      run: bazel test --test_env=RUST_BACKTRACE=1 --flaky_test_attempts=3 //rust/...
+      run: bazel test --test_env=RUST_BACKTRACE=full --flaky_test_attempts=3 //rust/...