hydra-queue-runner: Disable findBuildDependencyInQueue for now

Dependencies

• [2] WTUBAA5Q hydra-queue-runner: Handle restarted builds whose derivation is gone
• [*] 7YBYT2LQ
• [*] TPSCSZKX Speed up findBuildDependencyInQueue

Change contents

• edit in src/script/hydra-queue-runner at line 51
  [5.36]

  [2.0]
  + return undef; # FIXME