remove(grafana-agent): Remove grafana-agent because of EOL error

I am getting this error when trying to flake update nixos-modules: 'grafana-agent'
has been removed, as it only works with an EOL compiler and will become EOL during
the 25.05 release. Since we are currently not using it - we decided to remove it.

Author: galin-s

.github/workflows/reusable-update-flake-packages.yml

@@ -57,4 +57,4 @@ jobs:
         uses: metacraft-labs/nix-update-action@main
         with:
           token: ${{ steps.generate-token.outputs.token }}
-          blacklist: 'ci-matrix,folder-size-metrics,mcl,grafana-agent,validator-ejector'
+          blacklist: 'ci-matrix,folder-size-metrics,mcl,validator-ejector'

modules/default.nix

@@ -1,7 +1,6 @@
 {
   imports = [
     ./lido
-    ./grafana-agent-flow
     ./pyroscope
     ./folder-size-metrics
     ./shard-split

modules/grafana-agent-flow/default.nix

@@ -60,7 +60,6 @@
           random-alerts = pkgs.callPackage ./random-alerts { };
         }
         // optionalAttrs (system == "x86_64-linux" || system == "aarch64-darwin") {
-          grafana-agent = import ./grafana-agent { inherit inputs'; };
           secret = import ./secret { inherit inputs' pkgs; };
         }
         // optionalAttrs isLinux {