Fix the import C++ namespace indirectly test to make it expected to fail (#6076)

Imported namespace do not implicitly import its content, so lookup
inside them is expected to fail.

Author: bricknerb

toolchain/check/testdata/interop/cpp/import.carbon

@@ -30,20 +30,19 @@ import Cpp library "namespace.h";
 
 alias MyNamespaceAlias = Cpp.MyNamespace;
 
-// --- fail_todo_import_namespace_api.carbon
+// --- fail_import_namespace_api.carbon
 
 library "[[@TEST_NAME]]";
 
 import library "namespace_api";
 
 fn F() {
-  //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_namespace_api.carbon:[[@LINE+4]]:10: error: member name `MyClass` not found in `Cpp.MyNamespace` [MemberNameNotFoundInInstScope]
+  // Imports are not implicitly re-exported, so lookup is expected to fail.
+  // CHECK:STDERR: fail_import_namespace_api.carbon:[[@LINE+4]]:10: error: member name `MyClass` not found in `Cpp.MyNamespace` [MemberNameNotFoundInInstScope]
   // CHECK:STDERR:   var x: MyNamespaceAlias.MyClass;
   // CHECK:STDERR:          ^~~~~~~~~~~~~~~~~~~~~~~~
   // CHECK:STDERR:
   var x: MyNamespaceAlias.MyClass;
-  //@dump-sem-ir-end
 }
 
 // ============================================================================
@@ -112,26 +111,6 @@ fn F() {
   //@dump-sem-ir-end
 }
 
-// CHECK:STDOUT: --- fail_todo_import_namespace_api.carbon
-// CHECK:STDOUT:
-// CHECK:STDOUT: constants {
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: imports {
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: fn @F() {
-// CHECK:STDOUT: !entry:
-// CHECK:STDOUT:   name_binding_decl {
-// CHECK:STDOUT:     %x.patt: <error> = binding_pattern x [concrete]
-// CHECK:STDOUT:     %x.var_patt: <error> = var_pattern %x.patt [concrete]
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %x.var: ref <error> = var %x.var_patt [concrete = <error>]
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT:   %x: <error> = bind_name x, <error> [concrete = <error>]
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_todo_import_struct_api.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {