HADOOP-18168. . (#4140)


This moves off use of the purged s3a://landsat-pds bucket, so fixing tests
which had started failing.
* Adds a new class, PublicDatasetTestUtils to manage the use of public datasets.
* The new test bucket s3a://usgs-landsat/ is requester pays, so depends upon
  HADOOP-14661.

Consult the updated  test documentation when running against other S3 stores.

Contributed by Daniel Carl Jones
6 files changed