test(compiler): Ensure that ForLoopToParallelPass does not trigger fo…

…r scf.for with parallel = false

This ensures that the regression fixed by
3cd3dff is not reintroduced, which
caused the compiler to abort in `ForLoopToParallelPass` for `scf.for`
loops with iteration arguments, even if these were marked with the
attribute `parallel` set to `false`.

compilers/concrete-compiler/compiler/tests/check_tests/Transforms/scf-to-parallel.mlir

@@ -0,0 +1,18 @@
+// RUN: concretecompiler --split-input-file --action=dump-std --parallelize --parallelize-loops --skip-program-info --passes=for-loop-to-parallel --skip-program-info %s 2>&1| FileCheck %s
+
+func.func @bar() -> () {
+  %c0 = arith.constant 0 : index
+  %c1 = arith.constant 1 : index
+  %c4 = arith.constant 4 : index
+  %i0 = arith.constant 0 : i32
+  %i1 = arith.constant 1 : i32
+
+  // CHECK-NOT: scf.parallel
+  %0 = scf.for %iv = %c0 to %c4 step %c1 iter_args(%ia = %i0) -> i32 {
+    "Tracing.trace_plaintext"(%i0) : (i32) -> ()
+    %yld = arith.addi %ia, %i1 : i32
+    scf.yield %yld : i32
+  } {"parallel" = false }
+
+  return
+}