🤖 ci: drop linux hm activation from garnix

What:
- remove hm-activation linux check from garnix build list

Why:
- keep HM activation checks consolidated in GitHub Actions
- avoid split CI signal between Garnix and Actions

Tests:
- nix flake check --accept-flake-config (ok; warns linux checks omitted)

Author: DJTBOT

garnix.yaml

@@ -13,4 +13,3 @@ builds:
     - "checks.x86_64-linux.config-options"
     - "checks.x86_64-linux.config-validity"
     - "checks.x86_64-linux.package-contents"
-    - "checks.x86_64-linux.hm-activation"