Cherry-pick #15946 to 7.x: Remove debug logging from keystore (#15969)

The keystore is loaded before the configuration file is loaded, which
means that some debug messages are never printed, because logging is still
not initialized (logs will be discarded).

(cherry picked from commit 56924a3)

libbeat/keystore/keystore.go

@@ -22,7 +22,6 @@ import (
 	"fmt"
 
 	"github.com/elastic/beats/libbeat/common"
-	"github.com/elastic/beats/libbeat/logp"
 	ucfg "github.com/elastic/go-ucfg"
 )
 
@@ -87,7 +86,6 @@ func Factory(cfg *common.Config, defaultPath string) (Keystore, error) {
 		config.Path = defaultPath
 	}
 
-	logp.Debug("keystore", "Loading file keystore from %s", config.Path)
 	keystore, err := NewFileKeystore(config.Path)
 	return keystore, err
 }
@@ -122,7 +120,6 @@ func ResolverWrap(keystore Keystore) func(string) (string, error) {
 			return "", err
 		}
 
-		logp.Debug("keystore", "accessing key '%s' from the keystore", keyName)
 		return string(v), nil
 	}
 }