How to redirect to a link from a subdomain wildcard?

Question

Apache HTTP Server

There are 20 wildcard subdomains test1.domain.ru test2.domain.ru etc. and there are page addresses in the same number as domain.ru/cat/test1 domain.ru/cat/test2.
How to do rewrite with address autodetection? The client visits test1.domain.ru and the rewrite redirects the client to domain.ru/cat/test1, etc. Is it possible to implement this using regex expressions?