[TFLite] Fix resize bilinear tests by raising a too low error_threshold when align_corners is true

[Tessil]

Hi,

The '//tensorflow/lite/kernels/internal:resize_bilinear_test' is failing on our side with the following errors since commit 297ffd8:

tensorflow/lite/kernels/internal/resize_bilinear_test.cc:73: Failure
Expected: (relative_error) < (error_threshold), actual: 0.000531915 vs 0.0003
tensorflow/lite/kernels/internal/resize_bilinear_test.cc:73: Failure
Expected: (relative_error) < (error_threshold), actual: 0.000400641 vs 0.0003
tensorflow/lite/kernels/internal/resize_bilinear_test.cc:73: Failure
Expected: (relative_error) < (error_threshold), actual: 0.000674764 vs 0.0003
tensorflow/lite/kernels/internal/resize_bilinear_test.cc:73: Failure
 Expected: (relative_error) < (error_threshold), actual: 0.000558036 vs 0.0003
tensorflow/lite/kernels/internal/resize_bilinear_test.cc:73: Failure
Expected: (relative_error) < (error_threshold), actual: 0.000300481 vs 0.0003

The threshold when comparing the reference and optimized resize bilinear kernel with align_corners is too low. This PR raises it to 1e-3 as it seems the kernel is correct and the problem comes from the too tight threshold.

Thibaut

[abattery]

@Tessil Is this PR required because the current optimized kernels in TFLite have not succeeded with your system and configuration only? Or are you optimizing the kernels further?

If this failure happens at your environment only, could you share your testing environment's details to understand the problem better?

[Tessil]

It fails on our CI with the latest commit in the TF master branch without any further change.

It also fails locally on my desktop though the error is slightly different:

tensorflow/lite/kernels/internal/resize_bilinear_test.cc:73: Failure
Expected: (relative_error) < (error_threshold), actual: 0.000365497 vs 0.0003

The CI uses the tensorflow/tensorflow:custom-op-gpu-ubuntu16 docker image with USE_NEON enabled. My desktop uses g++ 7.5.0 without USE_NEON (Ubuntu 18.04).

Raising the kTestsToRun generates more similar errors on our side (can be useful for a quick test).

[abattery]

Thanks for sharing the details. :)