selftests/bpf: fix a test for snprintf() overflow
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 v5.15.61 by commit ad3e3212492c0d3cfb158d4a7cfc7b2427c553de, it was introduced in version v4.18 by commit c0fa1b6c3efc64b4ecfec658f95475fda650742e. For more details please see the references link.