[mlir][arith] Fix build after #171024

Author: matthias-springer

mlir/test/Integration/Dialect/Arith/CPU/test-apfloat-emulation-vector.mlir

@@ -3,7 +3,7 @@
 // mlir_apfloat_wrappers in a platform-independent way.
 
 // All floating-point arithmetics is lowered through APFloat.
-// RUN: mlir-opt %s --convert-arith-to-apfloat --convert-scf-to-vector | \
+// RUN: mlir-opt %s --convert-arith-to-apfloat --convert-scf-to-vector |
 // RUN:     --convert-scf-to-cf --convert-to-llvm | \
 // RUN: mlir-runner -e entry --entry-point-result=void \
 // RUN:             --shared-libs=%mlir_c_runner_utils \