-$moduleHandler->addModule('mymodule', 'modules/mymodule');
 $moduleHandler->load('mymodule');

<?php

use DrupalRector\Drupal11\Rector\Deprecation\RemoveModuleHandlerAddModuleCallsRector;
use Rector\Config\RectorConfig;

return RectorConfig::configure()
    ->withRules([
        RemoveModuleHandlerAddModuleCallsRector::class,
    ]);

Other rules in the drupal/core 11.2 set

• RemoveHandlerBaseDefineExtraOptionsRector - Remove overrides of the deprecated HandlerBase::defineExtraOptions() which has no replacement (drupal:11.2.0)
• RemoveCacheTagChecksumAssertionsRector - Remove deprecated CacheTagChecksumCount and CacheTagIsValidCount entries from assertMetrics() calls (deprecated in drupal:11.2.0, removed in drupal:12.0.0, no replacement).
• ViewsBlockItemsPerPageNoneToNullRector - Replace $block->setConfigurationValue('items_per_page', 'none') with NULL for Views block plugins.
• EntityFormModeEmptyDescriptionToNullRector - Replace empty-string description with NULL in EntityFormMode::create() calls (deprecated in drupal:11.2.0).
• RemoveRootFromCreateConnectionOptionsFromUrlRector - Replace deprecated $root argument in Connection::createConnectionOptionsFromUrl() calls with NULL
• RenameStopProceduralHookScanRector - Rename #[StopProceduralHookScan] attribute to #[ProceduralHookScanStop] and update its use statement (drupal:11.2.0)