kprobes: Remove obsoleted declaration for init_test_probes

The init_test_probes() have been removed since
commit e44e81c5 ("kprobes: convert tests to kunit"), and now
it is useless, so remove it.

Link: https://lore.kernel.org/all/20240826032552.4016314-1-cuigaosheng1@huawei.com/



Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>