We have had various reports of problems caused by the maxRetryTimeout
setting in the low-level REST client. Such setting was initially added
in the attempts to not have requests go through retries if the request
already took longer than the provided timeout.
The implementation was problematic though as such timeout would also
expire in the first request attempt (see #31834), would leave the
request executing after expiration causing memory leaks (see #33342),
and would not take into account the http client internal queuing (see #25951).
Given all these issues, it seems that this custom timeout mechanism
gives little benefits while causing a lot of harm. We should rather rely
on connect and socket timeout exposed by the underlying http client
and accept that a request can overall take longer than the configured
timeout, which is the case even with a single retry anyways.
This commit removes the `maxRetryTimeout` setting and all of its usages.
With #29331 we added support for the cluster health API to the
high-level REST client. The transport client does not support the level
parameter, and it always returns all the info needed for shards level
rendering. We have maintained that behaviour when adding support for
cluster health to the high-level REST client, to ease migration, but the
correct thing to do is to default the high-level REST client to
`cluster` level, which is the same default as when going through the
Elasticsearch REST layer.
This commit removes all the API methods that accept a `Header` varargs
argument, in favour of the newly introduced API methods that accept a
`RequestOptions` argument.
Relates to #31069
Lisa Cawley
Luca Cavanna