Change 'shaderrender' (glsl) tests to use a size of 128x128 rather than 100x100,…
… to avoid interpolation noise.
This is a slightly unusual bugfix, but I was seeing failures in the dEQP-VK.glsl.operator.binary_operator.bitwise_xor and dEQP-VK.glsl.operator.float_compare.lessThan/lessThanEqual (and GT/GEQ) tests, only in the fragment shader variants. These are both tests where a small interpolation difference can get magnified into a very large diff due to the nature of the operation, and this was causing these tests to fail. Using power-of-two dimensions reduces the frequency of GPU vs reference interpolation differences.
See merge request !225