[2.2.0] Checkmk Werk 16582 created: passwords: Fix internal server error when creating a password in CME with a non existent customer

Title: passwords: Fix internal server error when creating a password in CME with a non existent customer Class: fix Compatible: compat Component: rest-api Date: 1710234772 Edition: cre Level: 1 Version: 2.2.0p24 Previous this Werk, a status code 500 (Internal server error) was raised when creating a password with a non existent customer. This werk fixes that and now it returns a status code 400 (Bad request) with proper informaiton about the error