amazon-ssm-agent: remove overrideEtc parameter

This was meant to make amazon-ssm-agent work "out of the box" on non-NixOS
systems but the feature never really worked.

The problem is that amazon-ssm-agent looks for the files "amazon-ssm-agent.json"
and "seelog.xml" but the files in the package are named
"amazon-ssm-agent.json.template" and "seelog.xml.template". So even with
this overrideEtc = true it would not be able to find the config.

E.g. you'd get an error like

Error occurred fetching the seelog config file path:  open /nix/store/pyfxjr0i0hszcj9b6fqly6344zf9zhcb-amazon-ssm-agent-3.3.484.0/etc/amazon/ssm/seelog.xml: no such file or directory
on startup.

Removing this parameter from the from the package doesn't break things as it didn't work in the first place.

nixos/modules/services/misc/amazon-ssm-agent.nix

@@ -28,13 +28,7 @@ in {
 
   options.services.amazon-ssm-agent = {
     enable = mkEnableOption "Amazon SSM agent";
-
-    package = mkOption {
-      type = types.path;
-      description = "The Amazon SSM agent package to use";
-      default = pkgs.amazon-ssm-agent.override { overrideEtc = false; };
-      defaultText = literalExpression "pkgs.amazon-ssm-agent.override { overrideEtc = false; }";
-    };
+    package = mkPackageOption pkgs "amazon-ssm-agent" {};
   };
 
   config = mkIf cfg.enable {

pkgs/by-name/am/amazon-ssm-agent/package.nix

@@ -14,7 +14,6 @@
 , nixosTests
 , testers
 , amazon-ssm-agent
-, overrideEtc ? true
 }:
 
 let
@@ -96,9 +95,6 @@ buildGoModule rec {
       --replace "/sbin/shutdown" "shutdown"
 
     echo "${version}" > VERSION
-  '' + lib.optionalString overrideEtc ''
-    substituteInPlace agent/appconfig/constants_unix.go \
-      --replace '"/etc/amazon/ssm/"' '"${placeholder "out"}/etc/amazon/ssm/"'
   '' + lib.optionalString stdenv.isLinux ''
     substituteInPlace agent/managedInstances/fingerprint/hardwareInfo_unix.go \
       --replace /usr/sbin/dmidecode ${dmidecode}/bin/dmidecode