This commit removes `index.translog.flush_threshold_ops` and `index.translog.disable_flush`
in favor of `index.translog.flush_threshold_size`. The number of operations is meaningless by itself and
can easily be turned into a size value with knowledge of the data. Disabling the flush is only useful in
tests and we can set the size value to a really high value. If users really need to do this they can
also apply a very high value like `1PB`.
This change adds a Fixture class for use by gradle. A Fixture is an
external process that integration tests will use. It can be added as a
dependsOn for integTest, and will automatically be shutdown upon success
or failure, as well as relevant information dumped on failure. There is
also an example fixture in this change.
Simon Willnauer
Colin Goodheart-Smithe
Ryan Ernst
Boaz Leskes
Areek Zillur