kmsbasesdpendpoint: do not keep first negotiated session when it is released
kmsbasesdpendpoint: do not keep first negotiated session when it is released

Change-Id: I30277ed1583034bb8607448d2043d000fd0f47db

ESTOS/kms-core,Kurento/kms-core,Kurento/kms-core,ESTOS/kms-core,ESTOS/kms-core,Kurento/kms-core,ESTOS/kms-core,Kurento/kms-core