hydra-module.nix: Use startAt

Dependencies

• [2] T4DBPQOF hydra-module: Run hydra-init during hydra-init.service
• [3] 3FTM52B2 hydra-module: Always GC to have at least 100 GiB available.
• [4] ZYEFL36Q Ported/merged properties from the TUD configuration's hydra-module
• [*] D3MDJONY

Change contents

• edit in hydra-module.nix at line 249
  [3.2664]

  [6.5082]
  + startAt = "02:15";
• edit in hydra-module.nix at line 276
  [2.461]→[3.2994:3089](∅→∅),[3.1827]→[3.2994:3089](∅→∅)
  − "15 2 * * * root ${pkgs.systemd}/bin/systemctl start hydra-update-gc-roots.service"