Runner: VM details break CSV output format when not on GCP

[siddharth-krishna]

If run_benchmarks.py is run on ZIB (and perhaps also locally?) the output CSV format is messed up because the columns VM Instance Type and VM Zone have newlines in them. We should update the code so that if it is run anywhere other than GCP these fields are empty or "N/A". Example:

Benchmark,Size,Solver,Solver Version,Solver Release Year,Status,Termination Condition,Runtime (s),Memory Usage (MB),Objective Value,Max Integrality Violation,Duality Gap,Reported Runtime (s),Timeout,Hostname,Run ID,Timestamp,VM Instance Type,VM Zone,Solver benchmark version
pypsa-de-elec-uc,2-24h,gurobi,13.0.0,2025,ok,optimal,2741.674774666,4760.408,5984851101.057478,,,2740.912817955017,3600,htc-cmp223.zib.de,20260324_191531_htc-cmp223.zib.de,2026-03-24 19:15:32.480233,"html>
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