[x-project tests] Fix ambiguity in call to createStringError (NFC)

Fixes:

  https://lab.llvm.org/buildbot/#/builders/139/builds/66928/
  https://lab.llvm.org/buildbot/#/builders/216/builds/40166/

Author: JDevlieghere

cross-project-tests/debuginfo-tests/llvm-prettyprinters/gdb/llvm-support.cpp

@@ -18,7 +18,7 @@ llvm::MutableArrayRef<int> MutableArrayRef(Array);
 llvm::DenseMap<int, int> DenseMap = {{4, 5}, {6, 7}};
 llvm::StringMap<int> StringMap = {{"foo", 123}, {"bar", 456}};
 llvm::Expected<int> ExpectedValue(8);
-llvm::Expected<int> ExpectedError(llvm::createStringError({}, ""));
+llvm::Expected<int> ExpectedError(llvm::createStringError(""));
 std::optional<int> OptionalValue(9);
 std::optional<int> OptionalNone(std::nullopt);
 llvm::SmallVector<int, 5> SmallVector = {10, 11, 12};