selftests/bpf: Add test coverage for reg_set_min_max handling

Add a test case for the jmp32/k fix to ensure selftests have coverage.

Before fix:

  # ./vmtest.sh -- ./test_progs -t verifier_or_jmp32_k
  [...]
  ./test_progs -t verifier_or_jmp32_k
  tester_init:PASS:tester_log_buf 0 nsec
  process_subtest:PASS:obj_open_mem 0 nsec
  process_subtest:PASS:specs_alloc 0 nsec
  run_subtest:PASS:obj_open_mem 0 nsec
  run_subtest:FAIL:unexpected_load_success unexpected success: 0
  #492/1   verifier_or_jmp32_k/or_jmp32_k: bit ops + branch on unknown value:FAIL
  #492     verifier_or_jmp32_k:FAIL
  Summary: 0/0 PASSED, 0 SKIPPED, 1 FAILED

After fix:

  # ./vmtest.sh -- ./test_progs -t verifier_or_jmp32_k
  [...]
  ./test_progs -t verifier_or_jmp32_k
  #492/1   verifier_or_jmp32_k/or_jmp32_k: bit ops + branch on unknown value:OK
  #492     verifier_or_jmp32_k:OK
  Summary: 1/1 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20240613115310.25383-3-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>