Relax the checking of std::filesystem::create_directories for seed inputs dir.

Sometimes the seed inputs dir may exist if previous cleanup failed, but there is nothing wrong with reusing the previous dir.

The check on `error` later should be enough to ensure that the seed inputs dir exists.

PiperOrigin-RevId: 911341568

centipede/centipede_callbacks.cc

diff --git a/centipede/centipede_callbacks.cc b/centipede/centipede_callbacks.cc
index fab4212..e560369 100644
--- a/centipede/centipede_callbacks.cc
+++ b/centipede/centipede_callbacks.cc
@@ -634,8 +634,9 @@
     std::vector<ByteArray>& seeds) {
   const auto output_dir = std::filesystem::path{temp_dir_} / "seed_inputs";
   std::error_code error;
-  FUZZTEST_CHECK(std::filesystem::create_directories(output_dir, error));
-  FUZZTEST_CHECK(!error);
+  std::filesystem::create_directories(output_dir, error);
+  FUZZTEST_CHECK(!error) << "Failed to create seed inputs directory "
+                         << output_dir << ": " << error.message();
 
   std::string centipede_runner_flags = absl::StrCat(
       "CENTIPEDE_RUNNER_FLAGS=:dump_seed_inputs:test=", env_.test_name,