[MM-57194] Allow plugins to mark setting fields as secret (#27986)

Co-authored-by: Claudio Costa <cstcld91@gmail.com>

server/channels/api4/config_local.go

@@ -77,7 +77,7 @@ func localUpdateConfig(c *Context, w http.ResponseWriter, r *http.Request) {
 	}
 	auditRec.AddEventPriorState(&diffs)
 
-	newCfg.Sanitize()
+	c.App.SanitizedConfig(newCfg)
 
 	auditRec.Success()
 	c.LogAudit("updateConfig")