[HLSL][TEST] Fix root signature driver test on WSL (#161566)

Running those test with validation enabled, causes emitting an
additional intermediary object, which causes the checks to fail, since
it will emit 2 `obj`, instead of one `obj` and one `dxo`. This patch
changes the test to make sure validation is disabled, making the test
consistent across environments.

Author: joaosaffran

clang/test/Driver/dxc_frs.hlsl

@@ -1,10 +1,9 @@
-// RUN: %clang_dxc -T cs_6_0 /Fo %t.dxo /Frs %t.rs.dxo -### %s 2>&1 | FileCheck %s
+// RUN: %clang_dxc -Vd -T cs_6_0 /Fo %t.dxo /Frs %t.rs.dxo -### %s 2>&1 | FileCheck %s
 
 // Test to demonstrate extracting the root signature to the specified
 // output file with /Frs.
 
 // CHECK: "{{.*}}llvm-objcopy{{(.exe)?}}" "{{.*}}.obj" "{{.*}}.dxo" "--extract-section=RTS0={{.*}}.rs.dxo"
-
 [shader("compute"), RootSignature("")]
 [numthreads(1,1,1)]
 void EmptyEntry() {}

clang/test/Driver/dxc_rootsignature_target.hlsl

@@ -1,4 +1,4 @@
-// RUN: %clang_dxc -E EntryRS -T rootsig_1_1 /Fo %t.dxo -### %s 2>&1 | FileCheck %s --check-prefix=CMDS
+// RUN: %clang_dxc -Vd -E EntryRS -T rootsig_1_1 /Fo %t.dxo -### %s 2>&1 | FileCheck %s --check-prefix=CMDS
 
 // CMDS: "{{.*}}clang{{.*}}" "-cc1"
 // CMDS-SAME: "-triple" "dxilv1.1-unknown-shadermodel1.1-rootsignature"