Simplify our Normalizer story to have just a single, configurable
implementation.
* fold the features of `MergeNormalizer` into
`SimpleRegionNormalizer`, removing the intermediate abstract class.
* configuration keys for merge-only features now share a common
structure.
* add configuration to selectively disable normalizer split/merge
operations.
* `RegionNormalizer` now extends `Configurable` instead of creating a
new instance of `HBaseConfiguration` or snooping one off of other
fields.
* avoid the extra RPCs by using `MasterServices` instead of
`MasterRpcServices`.
* boost test coverage of all the various flags and feature
combinations.
Signed-off-by: Michael Stack <stack@apache.org>
Signed-off-by: Viraj Jasani <vjasani@apache.org>
Signed-off-by: huaxiangsun <huaxiangsun@apache.org>
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