Bug 35973: Correct wrong values for RedirectGuaranteeEmail system preference

Bug 35973: Correct wrong values for RedirectGuaranteeEmail system preference

The system preferences was added with 0/1 in sysprefs.sql is checked
as boolean. But the .pref file was added with yes/no which both
evaluate as strings to true.

This fixes the .pref file and includes a database update that sets
0 and 1 correctly for the value currently chosen in the pref.

To test:
* Make sure to update RedirectGuaranteeEmail to Enable/Don't enable
  before applying the patch
* Verify in the database, that the values was set to yes or no
  You can use a report like:
    SELECT * from systempreferences WHERE variable = "RedirectGuaranteeEmail";
* Apply patch and run database update
* Verify the value in the database was corrected:
  Yes = 1, No = 0
* Change the setting, verify the new value is stored correctly

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>