Worker: allow configuring executor CloudWatch group

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>

cmd/osbuild-worker/config.go

@@ -72,9 +72,10 @@ type pulpConfig struct {
 }
 
 type executorConfig struct {
-	Type       string `toml:"type"`
-	IAMProfile string `toml:"iam_profile"`
-	KeyName    string `toml:"key_name"`
+	Type            string `toml:"type"`
+	IAMProfile      string `toml:"iam_profile"`
+	KeyName         string `toml:"key_name"`
+	CloudWatchGroup string `toml:"cloudwatch_group"`
 }
 
 type workerConfig struct {