treewide: remove redundant quotes

nixos/modules/services/web-apps/icingaweb2/icingaweb2.nix

@@ -163,7 +163,7 @@ in {
 
   config = mkIf cfg.enable {
     services.phpfpm.poolConfigs = mkIf (cfg.pool == "${poolName}") {
-      "${poolName}" = ''
+      ${poolName} = ''
         listen = "${phpfpmSocketName}"
         listen.owner = nginx
         listen.group = nginx
@@ -188,7 +188,7 @@ in {
     services.nginx = {
       enable = true;
       virtualHosts = mkIf (cfg.virtualHost != null) {
-        "${cfg.virtualHost}" = {
+        ${cfg.virtualHost} = {
           root = "${pkgs.icingaweb2}/public";
 
           extraConfig = ''
@@ -215,7 +215,7 @@ in {
 
     # /etc/icingaweb2
     environment.etc = let
-      doModule = name: optionalAttrs (cfg.modules."${name}".enable) { "icingaweb2/enabledModules/${name}".source = "${pkgs.icingaweb2}/modules/${name}"; };
+      doModule = name: optionalAttrs (cfg.modules.${name}.enable) { "icingaweb2/enabledModules/${name}".source = "${pkgs.icingaweb2}/modules/${name}"; };
     in {}
       # Module packages
       // (mapAttrs' (k: v: nameValuePair "icingaweb2/enabledModules/${k}" { source = v; }) cfg.modulePackages)

nixos/modules/services/web-apps/icingaweb2/module-monitoring.nix

@@ -58,7 +58,7 @@ in {
     };
 
     backends = mkOption {
-      default = { "icinga" = { resource = "icinga_ido"; }; };
+      default = { icinga = { resource = "icinga_ido"; }; };
       description = "Monitoring backends to define";
       type = attrsOf (submodule ({ name, ... }: {
         options = {