Revert "arb_uniform_buffer_object: add random generated tests to list of shaders"

This reverts commit f46af358.

Random generated tests are only useful if they generate stable, reproducible sets of random functionality. This commit needs a stable random seed so that any failing tests can be rebuilt by others for investigation, bisection, etc.

Currently, these tests will sometimes a generate a test failure, which will pass or fail reliably depending on which random characteristics were selected at piglit compile time. This breaks flaky handling in CI systems. It is impossible to know if any failures are due to an incorrect test assumption of a faulty driver.