Revert "sec: deprecate some webPreference defaults to be secure-by-default (#14284)" (#14380)

This reverts commit 66d6ba8689.

lib/browser/api/web-contents.js

@@ -293,10 +293,6 @@ WebContents.prototype._init = function () {
     ipcMain.emit(channel, event, ...args)
   })
 
-  this.on('-deprecated-default', function (event, key, oldDefault, newDefault) {
-    deprecate.warnDefault(key, oldDefault, newDefault)
-  })
-
   // Handle context menu action request from pepper plugin.
   this.on('pepper-context-menu', function (event, params, callback) {
     // Access Menu via electron.Menu to prevent circular require.