They were remade as part of a cleanup
On 2020-01-31 (so almost exactly one year ago at the time of writing this), Rapid7 released this article, in which they explain the history of how
jtr_crack_fast and similar modules came to be.
If you don’t care for the article, and just want the synopsis: The modules were all renamed to
crack_ instead of
jtr_. You can also change whether or not you wish to use JtR or Hashcat as the backend, so that the commands are backend-independent. These new and improved commands also have other nice features added, such as
show_command, which allows you to show the command being executed in the backend. The article explains it in more detail.
This change has been in Metasploit since version 5.0.72.