okta: retain full email address as user.name (#13404)

The entityanalytics_okta integration retains the full email address
rather than only the username part of the address. This breaks being
able to correlate individual entities with events, in addition to
potentially allowing collision between non-identical users in events.
So simplify the code and just keep the whole thing.

Author: efd6

packages/okta/changelog.yml

@@ -1,4 +1,9 @@
 # newer versions go on top
+- version: "3.6.0"
+  changes:
+    - description: Set `user.name` from Okta `actor.alternateId` field without modification.
+      type: enhancement
+      link: https://github.com/elastic/integrations/pull/13404
 - version: "3.5.1"
   changes:
     - description: Fix request trace log removal.