Lower logging level when unpacking config in autodiscover (#37816) (#…

…37819)

When unpacking a config while applying the autodiscover config
template, sometimes a configuration template cannot be resolved at
that moment but will be resolved at a later stage. This commit brings
the logging level of this error back to debug as it can become too
verbose and not always means the config is invalid.

(cherry picked from commit eae57f9)

Co-authored-by: Tiago Queiroz <tiago.queiroz@elastic.co>

CHANGELOG.next.asciidoc

@@ -52,6 +52,7 @@ https://github.com/elastic/beats/compare/v8.8.1\...main[Check the HEAD diff]
 - Fix panic when MaxRetryInterval is specified, but RetryInterval is not {pull}35820[35820]
 - Support build of projects outside of beats directory {pull}36126[36126]
 - aws: Add credential caching for `AssumeRole` session tokens. {issue}37787[37787]
+- Lower logging level to debug when attempting to configure beats with unknown fields from autodiscovered events/environments {pull}[37816][37816]
 
 *Auditbeat*
 

libbeat/autodiscover/template/config.go

@@ -154,7 +154,7 @@ func ApplyConfigTemplate(event bus.Event, configs []*conf.C, options ...ucfg.Opt
 		var unpacked map[string]interface{}
 		err = c.Unpack(&unpacked, opts...)
 		if err != nil {
-			logp.Warn("autodiscover: Configuration template cannot be resolved: %v", err)
+			logp.Debug("autodiscover", "Configuration template cannot be resolved: %v", err)
 			continue
 		}
 		// Repack again: