RFC: Structure cicd/tcpsctpperf and add wrk2/nginx benchmark

[luisgerhorst]

Just a RFC for now to get feedback on the wr2/nginx-based benchmark (primarily useful to analyze the tail latency). A single loxilb connects a configurable number of servers with a configurable number of workers.

Work to be done:

• Actually use the validation-* scripts in validation.sh
  • Idea was to structure it while simultaneously making the scripts useable by themself (i.e., I do that in https://gitlab.cs.fau.de/un65esoq/bpf-spectre/-/blob/main/src/target-scripts/bench-loxilb.sh?ref_type=heads#L67). The scripts produce machine-readable output.
• Decide on wrk2/nginx parameters (nr. of workers/threads, payload size, percentile to consider).
  • On a 6-core 2.7GHz CPU I can get loxilb to 100% CPU with 2 nginx and 2 wrk2 threads executing 28k RPS with 1KiB (each server/client thread consuming <= 80% CPU in this scenario).
  • This does not consider the load on the BPF programs. I am not sure if loxilb running at 100% is actually the bottleneck here because I can achieve 50k RPS with 4 nginx/wrk2 threads.

[nik-netlox]

Thanks for enhancing this. Changes looks good.