Fix cascade-pattern-with-extension for cascade in site config

Also clean up the log handling in the integration tester, most notably lost logs during the config loading.

Fixes #12151

config/allconfig/allconfig.go

@@ -671,6 +671,13 @@ type Configs struct {
 	configLangs []config.AllProvider
 }
 
+func (c *Configs) Validate(logger loggers.Logger) error {
+	for p := range c.Base.Cascade.Config {
+		page.CheckCascadePattern(logger, p)
+	}
+	return nil
+}
+
 // transientErr returns the last transient error found during config compilation.
 func (c *Configs) transientErr() error {
 	for _, l := range c.LanguageConfigSlice {
@@ -969,7 +976,7 @@ func decodeConfigFromParams(fs afero.Fs, logger loggers.Logger, bcfg config.Base
 	})
 
 	for _, v := range decoderSetups {
-		p := decodeConfig{p: p, c: target, fs: fs, logger: logger, bcfg: bcfg}
+		p := decodeConfig{p: p, c: target, fs: fs, bcfg: bcfg}
 		if err := v.decode(v, p); err != nil {
 			return fmt.Errorf("failed to decode %q: %w", v.key, err)
 		}