Revert "Fix vulkan include path (flutter#4870)" (flutter#4872)

Breaks Linux and Mac build bots.

This reverts commit d9ec2de.

Author: rmacnak-google

vulkan/skia_vulkan_header.h

@@ -8,4 +8,4 @@
 #endif  // VK_USE_PLATFORM_ANDROID_KHR
 #endif  // __ANDROID__
 
-#include "vulkan/vulkan.h"
+#include "third_party/vulkan/src/vulkan/vulkan.h"