selftests/bpf: ensure all CI arches set CONFIG_BPF_KPROBE_OVERRIDE=y

Turns out CONFIG_BPF_KPROBE_OVERRIDE=y is only enabled in x86-64 CI, but
is not set on aarch64, causing CI failures ([0]).

Move CONFIG_BPF_KPROBE_OVERRIDE=y to arch-agnostic CI config.

  [0] https://github.com/kernel-patches/bpf/actions/runs/6122324047/job/16618390535

Fixes: 7182e564 ("selftests/bpf: Add kprobe_multi override test")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230912055928.1704269-1-andrii@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/config

@@ -4,6 +4,7 @@ CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC=y
 CONFIG_BPF=y
 CONFIG_BPF_EVENTS=y
 CONFIG_BPF_JIT=y
+CONFIG_BPF_KPROBE_OVERRIDE=y
 CONFIG_BPF_LIRC_MODE2=y
 CONFIG_BPF_LSM=y
 CONFIG_BPF_STREAM_PARSER=y

tools/testing/selftests/bpf/config.x86_64

@@ -20,7 +20,6 @@ CONFIG_BLK_DEV_THROTTLING=y
 CONFIG_BONDING=y
 CONFIG_BOOTTIME_TRACING=y
 CONFIG_BPF_JIT_ALWAYS_ON=y
-CONFIG_BPF_KPROBE_OVERRIDE=y
 CONFIG_BPF_PRELOAD=y
 CONFIG_BPF_PRELOAD_UMD=y
 CONFIG_BPFILTER=y