[maven-release-plugin] prepare release 0.69
[maven-release-plugin] prepare for next development iteration
Rewrite EXPLAIN to a VALUES query

This helps avoid bytecode generation failures when plan string is too large due
to max constant pool size being exceeded.
Remove use of dual metadata from interpreter tests
Remove use of dual connector from TestSqlStageExecution
Remove use of dual from TestSqlTaskExecution
Remove use of dual from TestSqlTaskManager
Remove use of dual from query and function tests
Remove use of dual from TestEffectivePredicateExtractor
Remove dual connector