fix: reference extracted Procfile

Rather than attempting to always extract the Procfile, reference the one that was extracted by the last deploy. This fixes issues where 'docker container cp' may fail intermittently for lord knows what reason.

Closes #4083

docs/development/plugin-triggers.md

@@ -1511,7 +1511,7 @@ set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
 
 - Description: Removes the extracted Procfile
 - Invoked by: `internally`
-- Arguments: `$APP $PROCFILE_PATH`
+- Arguments: `$APP`
 - Example:
 
 ```shell