Rename site information config to new naming convention

A spin-off issue from #1496542: Convert site information to config system, This issue's task is to properly rename configuration settings of the site information form to the new naming convention described in #1599554: Tutorial/guidelines for how to convert variables into configuration.

After #1496542: Convert site information to config system lands, this patch will need to be rerolled so that it can be reduced to only the configuration variable name changes.

To start this, is the patch that sun chx rerolled and that sun authored in from #1496542: Convert site information to config system.