selftests/bpf: Remove test_skb_cgroup_id.sh from TEST_PROGS

test_skb_cgroup_id.sh was deleted in
https://git.kernel.org/bpf/bpf-next/c/f957c230e173



It has to be removed from TEST_PROGS variable in
tools/testing/selftests/bpf/Makefile, otherwise install target fails.

Signed-off-by: Ihor Solodrai <ihor.solodrai@pm.me>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/bpf/20240916195919.1872371-1-ihor.solodrai@pm.me
Link: https://lore.kernel.org/bpf/Q3BN2kW9Kgy6LkrDOwnyY4Pv7_YF8fInLCd2_QA3LimKYM3wD64kRdnwp7blwG2dI_s7UGnfUae-4_dOmuTrxpYCi32G_KTzB3PfmxIerH8=@pm.me/


Signed-off-by: Alexei Starovoitov <ast@kernel.org>