* Samples - Added the caching sample
* Added the sample to presubmit tests
* Replaced the sample with the one that is compatible with the current compiler and execution caching
Currently the cached executions cannot be reused in the same pipeline due to the fact that the compiler generates unique output names for every task.
* Fixed the max_cache_staleness value
* Fixed the time format
* Set max_cache_staleness to 0
* Set max_cache_staleness to P0D
* Switched to 60-second work time to avoid rare but possible flakyness
* Switched parameter type to float
This makes it possible to add small random noise, so that the sample retries are separte (not implemented).
* Replaced the sample with a notebook to overcome sample test infra limitation
Currently only notebook can launch pipelines itself. Python code files can only compile the pipeline.
* Added a sample test config
Perhaps we should make them unnecessary.
* Fixed the pipeline parameter type