`/executable vcard_photo test`
Printed
`Invalid usage, see '/help card_photo' for details.`
So it used the subcommand instead of the command and lost one of the
letters as well.
This mistake got introduced in 60c197487.
Where we added helper functions for the various `/executable` functions.
Discovered by @H3rnand3zzz with correct solution.
Fix https://github.com/profanity-im/profanity/issues/1921