* Validation script batches only samples
In this change, the validation script will batch only sample generation.
For meta and documentation, it will always be iterative.
Also made changes to meta-codegen*.sh so conditionals which may invoke
maven are explicitly rooted.
* [ci] batch python-experimental, include new springboot option
* move tests to drone.io
* ls dir
* debug
* use bash
* use jdk 11 image
* move tests to drone.io
* use maven wrapper
* comment out scripts in circleci
* update dart samples
* remove commented tests
* update dart samples