Change assist app warning message text

    <!-- [CHAR_LIMIT=NONE] Warning message about security implications of setting an assistant,

         displayed as a dialog message when the user selects an assistant. -->

    <string name="assistant_security_warning"><xliff:g id="assistant_app_name">%s</xliff:g> will

        be able to read information about apps in use on your system, including information

        visible on your screen or accessible within the apps.</string>

    <string name="assistant_security_warning">The assistant will be able to read information about

        apps in use on your system, including information visible on your screen or accessible

        within the apps.</string>

    <!-- Label for the button to acknowledge assistant security implications. [CHAR LIMIT=30] -->

    <string name="assistant_security_warning_agree">Agree</string>