Bug 1804902: Allow for new option value in group webservices

For the 'hidemembers' and 'hidemembersfrommembers' webservice options

behatnotneeded

Change-Id: Ie2c400bd9e144a3ab369c0e6eeed5e6910c0b065
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>