This commit cleans up some parsing tests added from the High Level Rest Client: IndexResponseTests, DeleteResponseTests, UpdateResponseTests, BulkItemResponseTests.
These tests are now more uniform with the others test-from-to-XContent tests we have, they now shuffle the XContent fields before parsing, the asserting method for parsed objects does not used a Map<String, Object> anymore, and buggy equals/hasCode methods in ShardInfo and ShardInfo.Failure have been removed.