[clang] [HLSL] Make step, isinf, rsqrt overload tests stricter. NFC (PR #177697)

[Ashley Coleman via cfe-commits]

================
@@ -1,20 +1,29 @@
 // RUN: %clang_cc1 -std=hlsl202x -finclude-default-header -x hlsl -triple \
-// RUN:   dxil-pc-shadermodel6.3-library %s -emit-llvm -disable-llvm-passes \
-// RUN:   -o - | FileCheck %s
+// RUN:   dxil-pc-shadermodel6.3-library %s -emit-llvm\
----------------
V-FEXrt wrote:

nit:
```suggestion
// RUN:   dxil-pc-shadermodel6.3-library %s -emit-llvm \
```

https://github.com/llvm/llvm-project/pull/177697