User removal takes time because of SIS calls
During deleting user from a scalix it can take a long time because it waits when SIS will remove index.
Lets assume that user index folder is 500Mb it can took up to 1 min and more and omdelu will wait till SIS repsonsed when it finishes.
Suggestion make init indexes and remove indexes api/http calls async.
Server sends remove index or create SIS starts new thread and run create/delete index) in newly created thread
and sends to the server 200 ok task.
As a side effect server will never show if there were an error creating or deleting indexes in `omshowlog`
they will be only in scalix-sis-indexer.log file.