Revert "selftests/bpf: Add a cgroup prog bpf_get_ns_current_pid_tgid() test"

This reverts commit 4730b07e.

The test depends on commit eb166e52 "bpf: Allow helper
bpf_get_[ns_]current_pid_tgid() for all prog types", which was not part of the
stable 6.6 code base, and thus the test will fail. Revert it since it is a
false positive.

Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>