test: remove clightning plugin start timeout patch

Unneded because the timeout has been increased upstream:
https://github.com/ElementsProject/lightning/commit/ee3133f19885269985180bd20e0b9737c70cf86c

test/tests.nix

@@ -271,17 +271,6 @@ let
         scenarios.secureNode
         ../modules/presets/hardened-extended.nix
       ];
-
-      # Patch clightning to increase the plugin init timeout.
-      # Otherwise this test can fail on slower hardware.
-      nix-bitcoin.pkgOverlays = super: self: {
-        clightning = super.clightning.overrideAttrs (old: {
-          postPatch = old.postPatch + ''
-            substituteInPlace lightningd/plugin.c \
-              --replace-fail "#define PLUGIN_MANIFEST_TIMEOUT 60" "#define PLUGIN_MANIFEST_TIMEOUT 200"
-          '';
-        });
-      };
     };
 
     netnsBase = { config, pkgs, ... }: {