Turn EventLogging's logrotate config into template

EventLogging's logrotate config uses variables since

  eed057682ed856a4489f95d274c072e58fe64ff0

but is still included as file, so the variables are not rendered with
their values. Hence, we turn the file into a template.

Change-Id: Iad0d9982cee45a9ae1f423d7100eaccca6d7a20e