SCN verification breaks with non-default column families

PHOENIX-5645 introduced a verification step when using SCN to prevent going back farther than TTL or max lookback age. The implementation committed to 4.16 had a bug where the verification step caused an exception when the default column family wasn't present. I fixed this in the 4.14 backport of 5645, but the same fix needs to go in 4.16 as well. Rather than do another addendum to 5645, I'm opening a separate JIRA here.