Default logger and events logger use different timestamp formats

[belimawr]

This was tested with the latest main from Elastic-Agent and Beats

The default logger (user configurable) and the events logger are using different formats for the timestamp:

Default logger (RFC3339):
"@timestamp":"2024-11-06T21:01:18.537Z"
Event logger (ISO8601):
"@timestamp":"2024-11-06T16:01:03.105-0500"

There is a chance this has been like that since the events logger was introduced by #4549.

Standalone Beats might be affected by this as well.

[elasticmachine]

Pinging @elastic/elastic-agent (Team:Elastic-Agent)