fix(oidc): use _json prop when setting displayName (#6135)

* Fixes setting displayName from OIDC

Relates to: https://github.com/requarks/wiki/pull/6096

* Update authentication.js

---------

Co-authored-by: Nicolas Giard <github@ngpixel.com>

server/modules/authentication/oidc/authentication.js

@@ -29,7 +29,7 @@ module.exports = {
             profile: {
               ...profile,
               email: _.get(profile, '_json.' + conf.emailClaim),
-              displayName: _.get(profile, conf.displayNameClaim, ''),
+              displayName: _.get(profile, '_json.' + conf.displayNameClaim, '')
             }
           })
           if (conf.mapGroups) {