HentaiAtHome: use default JDK with ZGC support
HentaiAtHome: use default JDK with ZGC support

This patch uses default JDK for building/running HentaiAtHome, and
enables ZGC by default. The default Serial GC shipped with GraalVM
Community proves to be suboptimal for long-running servers. With this
change, my server quality rises above 8000 according to Hentai@Home
dashboard.

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs