Reduce number of Fernet log messages
Reduce number of Fernet log messages

This particular message gets quite repetitive as it's logged per token
creation & validation request. Once max_active_keys is reached, it has
little utility beyond letting you know that the number of active Fernet
keys is (still) correct.

Change-Id: I6f497a5defa3c1da5bda54aa5f9e7303a0352d83
Closes-Bug: 1452418

mahak/keystone,idjaw/keystone,ilay09/keystone,takeshineshiro/keystone,dstanek/keystone,maestro-hybrid-cloud/keystone,takeshineshiro/keystone,jonnary/keystone,dims/keystone,ilay09/keystone,klmitch/keystone,maestro-hybrid-cloud/keystone,himanshu-setia/keystone,openstack/keystone,dstanek/keystone,rajalokan/keystone,cernops/keystone,cernops/keystone,himanshu-setia/keystone,mahak/keystone,rajalokan/keystone,vivekdhayaal/keystone,ilay09/keystone,jamielennox/keystone,ajayaa/keystone,openstack/keystone,roopali8/keystone,roopali8/keystone,jonnary/keystone,klmitch/keystone,openstack/keystone,rajalokan/keystone,mahak/keystone,dstanek/keystone,jamielennox/keystone,ajayaa/keystone,vivekdhayaal/keystone,dims/keystone,vivekdhayaal/keystone,idjaw/keystone