TrigCost: Improve finding oks metadata in postprocessing
- save prescale keys as string
- save hostname to metadata every time when present, not only when oks details requested
- find racks based on computer names (hostnames)
Example: https://atlas-trig-cost.cern.ch/?dir=data22-cos&type=&tag=data22-cos&run=00414879&page=metadata
Related to ATR-24424