hydra: fix name of build jobset

Dependencies

• [2] U2BNO3C5 hydra: fix build job
• [3] YQWH4POV * Simplify.
• [4] T4LLYESZ * Nix expression for building Hydra.
• [5] Y2BFYLLK * Install the SQL schemata in $out/share/hydra/sql.
• [6] VM3TQZ65 * hydra: make manual.pdf
• [7] 3MDDGGSN * Install the manual.
• [8] HPIJ35SG

Change contents

• replacement in release.nix at line 35
  [2.42]→[3.1718:1759](∅→∅),[3.1718]→[3.1718:1759](∅→∅)
  − name = "hydra-${tarball.version}";
  [2.42]

  [2.43]
  + name = "hydra";
• edit in release.nix at line 67
  [3.237]→[3.3313:3389](∅→∅),[3.3313]→[3.3313:3389](∅→∅)
  − echo "nix-build none $out" >> $out/nix-support/hydra-build-products