Increase parallelism in unit tests to 4
Add timestamp with time zone minus interval year month operator
Move drop table logic to NativeMetadata
Static import query execution factories
Used shared executor for query execution
Refactor execution of data definition statements
Rename InMemoryMetadata to TestingMetadata
Remove useless check in NativeMetadata
Use checkType in NativeMetadata
Fix warnings in MetadataManager
Add assertion for simple DDL queries