Checkmk Werk 14651: Fix "KeyError('use_regular')"

ID: 14651 Title: Fix "KeyError('use_regular')" Component: Checks & agents Level: 1 Class: Bug fix Version: 2.2.0i1 If users configured a rule <i>"Encryption (Linux, Windows)"</i> without actually setting values in it and used the unencryted mode of the agent controller, the Checkmk service would go {CRIT}.