DEV: decrease log level of compile failures

We do not need to report his in logs, our failure mode is fine here.

lib/stylesheet/manager.rb

@@ -165,7 +165,10 @@ class Stylesheet::Manager
          source_map_file: source_map_filename
       )
     rescue SassC::SyntaxError => e
-      Rails.logger.error "Failed to compile #{@target} stylesheet: #{e.message}"
+
+      # we do not need this reported as we will report it in the UI anyway
+      Rails.logger.info "Failed to compile #{@target} stylesheet: #{e.message}"
+
       if %w{embedded_theme mobile_theme desktop_theme}.include?(@target.to_s)
         # no special errors for theme, handled in theme editor
         ["", nil]