When running cilium on kernels that were not compiled with CONFIG_BPF_EVENTS=y, no events are passed from BPF back to userspace, making hubble show no L3/L4 events, without error.

Some discussion of this can be found on #37480.

BPF_EVENTS was enabled and tested in a slim distro here: https://github.com/EmilyShepherd/kiOS/commit/9de663bfcfcf1ad4fa18fb1b15bb75007963bd8d.

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docs: Document hubble requirement on kernels with BPF_EVENTS compiled in