selftests/bpf: Shuffle cookies symbols in kprobe multi test

There's a kernel bug that causes cookies to be misplaced and
the reason we did not catch this with this test is that we
provide bpf_fentry_test* functions already sorted by name.

Shuffling function bpf_fentry_test2 deeper in the list and
keeping the current cookie values as before will trigger
the bug.

The kernel fix is coming in following changes.

Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20220615112118.497303-2-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>