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/auth/credentials.go

@@ -222,8 +222,8 @@ func GenerateCredentials() (accessKey, secretKey string, err error) {
 		return "", "", err
 	}
 
-	secretKey = strings.Replace(string([]byte(base64.StdEncoding.EncodeToString(keyBytes))[:secretKeyMaxLen]),
-		"/", "+", -1)
+	secretKey = strings.ReplaceAll(string([]byte(base64.StdEncoding.EncodeToString(keyBytes))[:secretKeyMaxLen]),
+		"/", "+")
 
 	return accessKey, secretKey, nil
 }