32-bit qemu can only do 2047 MB

Dependencies

• [2] LZVO64YG Merge in the first bits of the API work
• [3] 7C6HSXUQ * Start of a regression test for Hydra.
• [4] YQWH4POV * Simplify.
• [*] T4LLYESZ * Nix expression for building Hydra.

Change contents

• replacement in release.nix at line 180
  [2.457]→[2.457:501](∅→∅)
  − virtualisation.memorySize = 2048;
  [2.457]

  [2.501]
  + virtualisation.memorySize = 2047;