Figure out which core update broke Group2to3UpdateTest

Hmm, just noticed something. Wouldn't it be funny if I got to don my hotdog suit.

Locally seeing this fail, which is after upgrading to recent core versions:

Base fields are already gone from group_content map
Failed asserting that null is identical to Array &0 [
    'group_roles' => Array &1 [
        'type' => 'entity_reference',
        'bundles' => Array &2 [
            'class-group_membership' => 'class-group_membership',
            'group_content_type_0055e25dd2326' => 'group_content_type_0055e25dd2326',
        ],
    ],
    'field_short_field' => Array &3 [
        'type' => 'string',
        'bundles' => Array &4 [
            'class-group_membership' => 'class-group_membership',
        ],
    ],
    'field_really_long_field_title_00' => Array &5 [
        'type' => 'string',
        'bundles' => Array &6 [
            'class-group_membership' => 'class-group_membership',
        ],
    ],
].

So this code is new:

/**
 * Install Help Search module if the Search and Help modules are installed.
 */
function search_update_11401(): void {
  $module_handler = \Drupal::moduleHandler();
  // Search help may already have been installed by sites on 11.4.0 or 11.4.1.
  if ($module_handler->moduleExists('search_help')) {
    return;
  }
  if ($module_handler->moduleExists('help')) {
    \Drupal::service('module_installer')->install(['search_help']);
  }
}

And that install() call triggers:

  #[Hook('modules_installed')]
  public function modulesInstalled(array $modules, bool $is_syncing): void {
    // Only create config objects while config import is not in progress.
    if (!$this->configInstaller->isSyncing()) {
      $this->groupRelationTypeManager->installEnforced();
    }
  }

Apparently too early during the test, as it's then trying to create the group roles field in GroupMembershipPostInstall but the storage does not exist yet. So $field_storage = $fsc_storage->load('group_relationship.group_roles'); looks for the new storage, but can't find it.

Okay so with some local changes I can get 3 cases to fail, two go green after I revert #3564969: Static cache field storage definitions

1. testEntityReferenceFields -> goes green after revert
2. testFieldStorages -> goes green after revert
3. testBundleFieldMap -> still red with error from above

#3045509: EntityFieldManager key/value field map gets out of sync, doesn't recognise bundle fields was the other culprit, with the following CR: https://www.drupal.org/node/3591180

Some days are fun, some days are not. This one was not :/