Fix hydra-queue-runner --build-one

Dependencies

• [2] MHVIT4JY Split hydra-queue-runner.cc more
• [3] YR2IM6Y5 Temporarily disable machines after a connection failure
• [4] TPNHTE5V Remove obsolete Builds columns and provide accurate "Running builds"

Change contents

• replacement in src/hydra-queue-runner/builder.cc at line 94
  [2.3421]→[2.3421:3460](∅→∅)
  − bool quit = build->id == buildOne;
  [2.3421]

  [2.3460]
  + bool quit = build->id == buildOne && step->drvPath == build->drvPath;