refactor: drop the minimizer list helper nothing calls any more

Its only caller was the guard that asked whether anything minified at all, and that question has no answer to give now that something always does. Its own description still said an empty list was `minify: false`, which is no longer a thing to say.

Author: alexander-akait

src/index.js

@@ -1468,17 +1468,6 @@ class MinimizerPlugin {
     return this.generators().some((one) => one.type !== "asset");
   }
 
-  /**
-   * The minimizers as a list, whichever shape they were written in. Empty is
-   * `minify: false`, which is what every pass over them then does nothing for.
-   * @private
-   * @param {EXPECTED_ANY} implementation one implementation, or an array
-   * @returns {EXPECTED_ANY[]} them
-   */
-  minimizerImplementations(implementation) {
-    return Array.isArray(implementation) ? implementation : [implementation];
-  }
-
   /**
    * Every name the functions this plugin runs mark an asset with, which is
    * what stats have to know how to print.

types/index.d.ts

@@ -133,14 +133,6 @@ declare class MinimizerPlugin<T = import("terser").MinifyOptions> {
    * @returns {boolean} true when one does
    */
   private hasModuleGenerator;
-  /**
-   * The minimizers as a list, whichever shape they were written in. Empty is
-   * `minify: false`, which is what every pass over them then does nothing for.
-   * @private
-   * @param {EXPECTED_ANY} implementation one implementation, or an array
-   * @returns {EXPECTED_ANY[]} them
-   */
-  private minimizerImplementations;
   /**
    * Every name the functions this plugin runs mark an asset with, which is
    * what stats have to know how to print.