KUDU-236 (part 3). Enable tablet history GC by default
KUDU-236 (part 3). Enable tablet history GC by default

Change-Id: Id81d9bf0d1b33d7d2384e101d10cfc299491f43a
Reviewed-on: http://gerrit.cloudera.org:8080/3983
Tested-by: Kudu Jenkins
Reviewed-by: Todd Lipcon <2c763d726a8c2f6afda9be7e0e56a2caa6bb5e6b@apache.org>

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