Fluentd has a default timeout of 5s for flushing data to ElasticSearch.
If there is a significant backlog of unsent log messages, this timeout
can be exceeded, resulting in Fluentd failing to make further progress.

Raise the default timeout to 60s.

This patch adopts the configuration parameters previously proposed by
Krzysztof Klimonda.

Closes-Bug: #1983031
Closes-Bug: #1896611
Change-Id: I1aaab654a5a0752fccef2cfb8cc0bde4a0ee2562