Fix Vulkan tests after GrContextFactory move to sk_gpu_test

Fix Vulkan tests after GrContextFactory move to sk_gpu_test

BUG=skia:
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Review URL: https://codereview.chromium.org/1844983003
diff --git a/tests/VkUploadPixelsTests.cpp b/tests/VkUploadPixelsTests.cpp
index 53d9cfc..a509978 100644
--- a/tests/VkUploadPixelsTests.cpp
+++ b/tests/VkUploadPixelsTests.cpp
@@ -16,6 +16,7 @@
 #include "Test.h"
 #include "vk/GrVkGpu.h"
 
+using sk_gpu_test::GrContextFactory;
 
 void fill_pixel_data(int width, int height, GrColor* data) {