Fix the test to use the right uniform location mTexture2DUniformLocation and mTextureCubeUniformLocation are uniform locations retrieved from the TextureCubeTest.mProgram. We should get the location from the shader program that the current test uses. Bug: angleproject:401546698 Change-Id: I7c5f022a9fab58572cae2e78fc328c1c0f74f977 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6502892 Reviewed-by: Amirali Abdolrashidi <abdolrashidi@google.com> Commit-Queue: Yuxin Hu <yuxinhu@google.com>