selftests/bpf: fix memory leak of lsm_cgroup
This is an automated ID intended to aid in discovery of potential security vulnerabilities. The actual impact and attack plausibility have not yet been proven. This ID is fixed in Linux Kernel version v6.0.16 by commit ca80a999695b00a53025fc96589410b3bfc3a953, it was introduced in version v6.0 by commit dca85aac8895708b74c7f2264e3ab5048c02b8b2. For more details please see the references link.