Dropped permutation number for full leb16-encoded defines

This is probably how the test runner should have been implemented in the
first place, but it took a few tries to get here.

This makes it so the test identifier, which is a bit longer now, fully
encodes the state of the defines in the test. This removes the need for
the extra geometry field and allows reproduction of tests with custom
defines at runtime.

The test runner may have already seemed like a solved problem, but these
changes are really to enable repurposing the test runner as a bench
runner.