sql-client-defaults.yaml should be removed from dist

According to https://cwiki.apache.org/confluence/display/FLINK/FLIP-163%3A+SQL+Client+Improvements#FLIP163:SQLClientImprovements-Compatibility,Deprecation,andMigrationPlan, the sql-client-defaults.yaml will be removed since 1.13. However, it is still there. I think this will make users misunderstand that it is still encouraged to be used. Besides, the default result of SET; command will contain lots of DEPRECATE informations which is confusing.