selftests/bpf: Migrate LOAD_REJECT test cases to prog_tests

Move LOAD_REJECT test cases from test_sock.c to an equivalent set of
verifier tests in progs/verifier_sock.c.

Signed-off-by: Jordan Rife <jrife@google.com>
Link: https://lore.kernel.org/r/20241022152913.574836-3-jrife@google.com


Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>