crostini: Log the error reason when we fail to create a container.

Bug: None
Test: Manual, check logs after failing to create a container
Change-Id: I56d456878fe61156307c7060f844477efa8b330e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1983693
Auto-Submit: David Munro <davidmunro@google.com>
Commit-Queue: Nic Hollingum <hollingum@google.com>
Reviewed-by: Nic Hollingum <hollingum@google.com>
Cr-Commit-Position: refs/heads/master@{#728647}

chrome/browser/chromeos/crostini/crostini_manager.cc

@@ -2524,6 +2524,12 @@ void CrostiniManager::OnLxdContainerCreated(
       break;
   }
 
+  if (result != CrostiniResult::SUCCESS) {
+    LOG(ERROR) << "Failed to create container. VM: " << signal.vm_name()
+               << " container: " << signal.container_name()
+               << " reason: " << signal.failure_reason();
+  }
+
   InvokeAndErasePendingContainerCallbacks(&create_lxd_container_callbacks_,
                                           signal.vm_name(),
                                           signal.container_name(), result);