add gocritic/ruleguard checks back again, cleanup code. (#13665)

- remove some duplicated code
- reported a bug, separately fixed in #13664
- using strings.ReplaceAll() when needed
- using filepath.ToSlash() use when needed
- remove all non-Go style comments from the codebase

Co-authored-by: Aditya Manthramurthy <donatello@users.noreply.github.com>

internal/event/config.go

@@ -318,7 +318,7 @@ func ParseConfig(reader io.Reader, region string, targetList *TargetList) (*Conf
 	}
 
 	config.SetRegion(region)
-	//If xml namespace is empty, set a default value before returning.
+	// If xml namespace is empty, set a default value before returning.
 	if config.XMLNS == "" {
 		config.XMLNS = "http://s3.amazonaws.com/doc/2006-03-01/"
 	}