[REF] Very minor cleanup

[eileenmcnaughton]

Overview

This change just removes an unused variable & uses our shorter hook pattern

Before

 // CRM-9137
    if (!empty($params['id'])) {
      CRM_Utils_Hook::pre('edit', 'Activity', $params['id'], $params);
    }
    else {
      CRM_Utils_Hook::pre('create', 'Activity', NULL, $params);
    }

After

 $action = empty($params['id']) ? 'create' : 'edit';
  CRM_Utils_Hook::pre($action, 'Activity', $params['id'] ?? NULL, $params);

Technical Details

Comments

[civibot]

(Standard links)

• If this is your first pull-request for CiviCRM, please browse CONTRIBUTING.md for information about the development and testing processes.
• If you are reviewing this pull-request, you may wish to consult the test sites and the Review Standards (long template, short template).