selftests/bpf: Add tests with stack ptr register in conditional jmp

Add two tests:
  - one test has 'rX <op> r10' where rX is not r10, and
  - another test has 'rX <op> rY' where rX and rY are not r10
    but there is an early insn 'rX = r10'.

Without previous verifier change, both tests will fail.

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250524041340.4046304-1-yonghong.song@linux.dev