Print excluded rules from CBO

HIVE-25880 introduced a configuration parameter for excluding CBO rules based on a regex on their description.

Calcite logs when a rule is excluded (see AbstractRelOptPlanner.java#L316 and VolcanoRuleCall.java#L169).

To ease investigations, this should be complemented by printing the regex used (if not blank) in Hive DEBUG logs, and the same in CBO information (i.e., EXPLAIN CBO's output).