sssd-kcm cannot handle big tickets

Issue

• If there is a ticket stored in kcm with many service principals then it can easily reach hardcoded limit 2KiB.
  a) the hardcoded limit does not make sense because It is configurable in sssd-secrets (man sssd-secrets -> max_payload_size)
  b) limit is too low and therefore unusable in real environment. (it's 8 times lower then default limit in sssd-secrets