selftests/bpf: Test invariants on JSLT crossing sign

selftests/bpf: Test invariants on JSLT crossing sign

The improvement of the u64/s64 range refinement fixed the invariant
violation that was happening on this test for BPF_JSLT when crossing the
sign boundary.

After this patch, we have one test remaining with a known invariant
violation. It's the same test as fixed here but for 32 bits ranges.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Link: https://lore.kernel.org/r/ad046fb0016428f1a33c3b81617aabf31b51183f.1753695655.git.paul.chaignon@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>