Remove plugin search feature (#14759)

Co-authored-by: SUZUKI Sosuke <aosukeke@gmail.com>

scripts/utils/generate-schema.js

@@ -80,19 +80,6 @@ function optionToSchema(option) {
   }
   if (option.array) {
     schema = wrapWithArraySchema(schema);
-
-    // #10274
-    if (option.name === "pluginSearchDirs") {
-      schema = {
-        oneOf: [
-          schema,
-          {
-            enum: [false],
-            description: "Disable plugin autoloading.",
-          },
-        ],
-      };
-    }
   }
   return {
     description: option.description,