Suppress flaky order-dependent BufferZeroInitTest.PaddingInitialized.

- Only suppressing for Linux/Vulkan/Nvidia platforms for now as those are the reproducable ones. The issue could be larger though.

Bug: dawn:1214
Change-Id: I56f29fdef912b0857b33bb81d391a82702750b47
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/71360
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Loko Kung <lokokung@google.com>

src/tests/end2end/BufferZeroInitTests.cpp

@@ -1139,6 +1139,7 @@ TEST_P(BufferZeroInitTest, SetVertexBuffer) {
 // still see zeros at the end of the buffer.
 TEST_P(BufferZeroInitTest, PaddingInitialized) {
     DAWN_SUPPRESS_TEST_IF(IsANGLE());  // TODO(crbug.com/dawn/1084).
+    DAWN_SUPPRESS_TEST_IF(IsLinux() && IsVulkan() && IsNvidia());  // TODO(crbug.com/dawn/1214).
 
     constexpr wgpu::TextureFormat kColorAttachmentFormat = wgpu::TextureFormat::RGBA8Unorm;
     // A small sub-4-byte format means a single vertex can fit entirely within the padded buffer,