NEXUS-6647: Add "cached until" to NFC not found message

Backport of original commit
b09e6b3fb450543fbc7424f88215de3972ce5f5d
Merge pull request #573 from sonatype/nexus-2.9.x-NEXUS-6647-describe-nfc-ttl

REVIEW: [2.9] NEXUS-6647: Tell the user when NFC entry will expire