Use BPF_PROG_TYPE_TRACING programs for kernels >= 5.5

Starting from kernel 5.5, a new type of bpf programs is supported, called BPF_PROG_TYPE_TRACING, which uses fentry/fexit for attachment (https://lwn.net/Articles/804937/)
Such programs have zero overhead compared to kprobes, and are thus preferable.
We should use these as the default for kernels >= 5.5

Start by locating the existing kprobe attachment setup and the kernel-version checks in the repository; the issue does not name specific files or tests. The work is done when kernels >= 5.5 use BPF_PROG_TYPE_TRACING with fentry/fexit by default, while the existing behavior remains available where needed.

Written by the indexing model from the issue text.