Undo the deletion of FF client and address issues from reviewer

docs/tutorial/PreviewFeatures.md

...va/org/opengroup/osdu/indexer/cache/FeatureFlagCache.java

...ava/org/opengroup/osdu/indexer/util/AugmenterSetting.java

...opengroup/osdu/indexer/util/BooleanFeatureFlagClient.java

...osdu/indexer/service/StorageIndexerPayloadMapperTest.java

...group/osdu/indexer/service/mock/PartitionFactoryMock.java

...roup/osdu/indexer/service/mock/PartitionProviderMock.java

...group/osdu/indexer/util/BooleanFeatureFlagClientTest.java

...ndexer/util/geo/decimator/DecimationSettingCacheTest.java