selftests/bpf: Add a test for arena range tree algorithm

commit e58358af upstream.

Add a test that verifies specific behavior of arena range tree
algorithm and adjust existing big_alloc1 test due to use
of global data in arena.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/20241108025616.17625-3-alexei.starovoitov@gmail.com


Signed-off-by: Yifei Liu <yifei.l.liu@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>