use max function to improve csql performance

[pjfanning]

• relates to Reverse order query causes performance bottleneck of cassandra cluster #240
• similar to Optimize query of highest seq number akka/akka-persistence-jdbc#401

The max function requires a min of Cassandra 2.2 and we can release note that. https://en.wikipedia.org/wiki/Apache_Cassandra (2.2 was released in 2015)

[pjfanning]

Looks like this is not going to work:

java.lang.IllegalArgumentException: sequence_nr is not a column in this row
	at com.datastax.oss.driver.internal.core.cql.DefaultRow.firstIndexOf(DefaultRow.java:112)
	at com.datastax.oss.driver.api.core.data.GettableByName.getLong(GettableByName.java:312)
	at org.apache.pekko.persistence.cassandra.journal.CassandraJournal.find$1$$anonfun$2$$anonfun$1(CassandraJournal.scala:687)
	at scala.Option.map(Option.scala:242)
	at org.apache.pekko.persistence.cassandra.journal.CassandraJournal.find$1$$anonfun$2(CassandraJournal.scala:687)

[pjfanning]

Looks like this is not going to work:

java.lang.IllegalArgumentException: sequence_nr is not a column in this row
	at com.datastax.oss.driver.internal.core.cql.DefaultRow.firstIndexOf(DefaultRow.java:112)
	at com.datastax.oss.driver.api.core.data.GettableByName.getLong(GettableByName.java:312)
	at org.apache.pekko.persistence.cassandra.journal.CassandraJournal.find$1$$anonfun$2$$anonfun$1(CassandraJournal.scala:687)
	at scala.Option.map(Option.scala:242)
	at org.apache.pekko.persistence.cassandra.journal.CassandraJournal.find$1$$anonfun$2(CassandraJournal.scala:687)

I think I have a fix for this