src: remove unused variable in node_contextify

Currently the following warning is show when building:
../src/node_contextify.cc:642:10:
warning: unused variable 'display_errors' [-Wunused-variable]

    bool display_errors = maybe_display_errors.ToChecked();

This commit removes the unused variable which became unused in commit
aeddc36 ("src: remove tracking for
exception arrow data").

Refs: nodejs#17394

src/node_contextify.cc

@@ -629,7 +629,6 @@ class ContextifyScript : public BaseObject {
     MaybeLocal<String> filename = GetFilenameArg(env, options);
     MaybeLocal<Integer> lineOffset = GetLineOffsetArg(env, options);
     MaybeLocal<Integer> columnOffset = GetColumnOffsetArg(env, options);
-    Maybe<bool> maybe_display_errors = GetDisplayErrorsArg(env, options);
     MaybeLocal<Uint8Array> cached_data_buf = GetCachedData(env, options);
     Maybe<bool> maybe_produce_cached_data = GetProduceCachedData(env, options);
     MaybeLocal<Context> maybe_context = GetContext(env, options);
@@ -639,7 +638,6 @@ class ContextifyScript : public BaseObject {
       return;
     }
 
-    bool display_errors = maybe_display_errors.ToChecked();
     bool produce_cached_data = maybe_produce_cached_data.ToChecked();
 
     ScriptCompiler::CachedData* cached_data = nullptr;