Beats common backoff behavior

[urso]

The different outputs have different backoff settings and behaviour on error and when to backoff. The redis output does not even support exponential backoff.

Update all outputs, in order to have similar backoff behaviour.

[urso]

#7781 adds backoff support to the redis output.

[ppf2]

While this is not an "output" per say, the Beats monitoring connection to Elasticsearch (#7966) can use an exponential backoff policy as well.

[urso]

Closing. There has been some improvements thanks to @ph.