We need the ability to use different CloudWatch group for the
osbuild-executor on Fedora workers in staging and production
environment.
Extend the worker confguration to allow configuring the CloudWatch group
name used by the osbuild-executor. Extend the secure instance code to
instruct cloud-init via user data to create /tmp/cloud_init_vars file
with the CloudWatch group name in the osbuild-executor instance, to make
it possible for the executor to configure its logging differently based
on the value.
Cover new changes by unit tests.
Signed-off-by: Tomáš Hozza <thozza@redhat.com>