Clarify the log message on batch cleanup failure.

The previous message indicates timeout, which is not always the reason why the wait fails - there could be other low-level reasons such as broken pipes.

PiperOrigin-RevId: 853256871

centipede/centipede_callbacks.cc

diff --git a/centipede/centipede_callbacks.cc b/centipede/centipede_callbacks.cc
index 010eaf2..3824fa5 100644
--- a/centipede/centipede_callbacks.cc
+++ b/centipede/centipede_callbacks.cc
@@ -500,11 +500,12 @@
   if (should_clean_up) {
     exit_code = [&] {
       if (!cmd.is_executing()) return EXIT_FAILURE;
-      FUZZTEST_LOG(ERROR) << "Cleaning up the batch execution.";
+      FUZZTEST_LOG(ERROR) << "Cleaning up the batch execution with timeout: "
+                          << kCommandCleanupTimeout;
       cmd.RequestStop();
       const auto ret = cmd.Wait(absl::Now() + kCommandCleanupTimeout);
       if (ret.has_value()) return *ret;
-      FUZZTEST_LOG(ERROR) << "Batch execution cleanup failed to end in 60s.";
+      FUZZTEST_LOG(ERROR) << "Failed to wait for the batch execution cleanup.";
       return EXIT_FAILURE;
     }();
     command_contexts_.erase(