fix(bench): swap validator network bindings with identities

[decofe]

Summary

• add isolated bench-e2e switches for datadir, CPU, validator-identity, and RPC-ingress swaps
• swap the complete validator network binding when identities are exchanged, preventing authenticated consensus peer rejection
• record diagnostic configuration in benchmark artifacts

Validation

• smoke-tested the corrected identity swap: both peers authenticated and the chain advanced
• completed three-pair 100 GiB existing-recipient comparisons for control, identity, CPU, datadir, and RPC variants
• identity, CPU, and RPC aggregate validation metrics were neutral; the datadir variant regressed validation p50/p90/p99 by 11.6%/10.7%/27.0%

Prompted by: @onbjerg