Completely removes S3Guard support from the S3A codebase.
If the connector is configured to use any metastore other than
the null and local stores (i.e. DynamoDB is selected) the s3a client
will raise an exception and refuse to initialize.
This is to ensure that there is no mix of S3Guard enabled and disabled
deployments with the same configuration but different hadoop releases
-it must be turned off completely.
The "hadoop s3guard" command has been retained -but the supported
subcommands have been reduced to those which are not purely S3Guard
related: "bucket-info" and "uploads".
This is major change in terms of the number of files
changed; before cherry picking subsequent s3a patches into
older releases, this patch will probably need backporting
first.
Goodbye S3Guard, your work is done. Time to die.
Contributed by Steve Loughran.
