Fix test fail after pulldown (#20734)

Most likely after commit bb1b82a
diagnostics show entities nested inside anonymous unions when previously
this nesting information was skipped over.

Author: premanandrao

sycl/test/esimd/regression/simd_wrapper.cpp

@@ -13,7 +13,7 @@ using namespace sycl::ext::intel::esimd;
 
 struct SimdWrapper {
   union {
-    // expected-note-re@+1 {{copy constructor of 'SimdWrapper' is implicitly deleted because variant field 'SimdWrapper::(anonymous struct at {{.*}})' has a non-trivial copy constructor}}
+    // expected-note-re@+1 {{copy constructor of 'SimdWrapper' is implicitly deleted because variant field 'SimdWrapper::(anonymous union)::(anonymous struct at {{.*}})' has a non-trivial copy constructor}}
     struct {
       simd<int, 4> v1;
     };