matrix: remove feature_report_to_moderators as it was removed #540

Job	Run time
check (NixOS/nixpkgs, nixos-unstable)	9m 28s
check (NixOS/nixpkgs, nixos-25.11)	5m 20s
check (NuschtOS/nuschtpkgs, backports-25.11)	7m 13s
check (SuperSandro2000/nixpkgs, nixos-unstable)	9m 38s
check (NuschtOS/nuschtpkgs, nixos-unstable)	8m 16s
	39m 55s

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