Allow for evaluator_pure_eval to be configured

Dependencies

• [2] VUYJ47EV hydra-eval-jobs: Parallelize
• [3] NQPGIRXX Revert "hydra-eval-jobs -> nix eval-hydra-jobs"

Change contents

• edit in src/hydra-eval-jobs/hydra-eval-jobs.cc at line 276
  [3.7695]

  [3.7765]
  +

  + auto pureEval = config->getBoolOption("evaluator_pure_eval", myArgs.flake);
• replacement in src/hydra-eval-jobs/hydra-eval-jobs.cc at line 288
  [3.8178]→[3.8178:8224](∅→∅)
  − evalSettings.pureEval = myArgs.flake;
  [3.8178]

  [2.7012]
  + evalSettings.pureEval = pureEval;