Describe the bug
${{ github.action_path }} points to a location in the host filesystem of the github runner host. Not to /__w/_actions/...

To Reproduce
Steps to reproduce the behavior:

1. Create a custom container.
2. Create a workflow that uses the custom docker container on a self-hosted runner.
3. Try to follow the guide for the new composite actions that requires to use ${{ github.action_path }}, for example to locate a shell script of a composite action.

Expected behavior
The shell script is found and executed, just like when doing this with a normal ubuntu-latest runner.

Runner Version and Platform

v2.273.4 on Linux.

OS of the machine running the runner? OSX/Windows/Linux/...
Linux.

What's not working?

(...)
##[error]Process completed with exit code 127.
Run pylot-tech/actions_checkout@v1
/__w/_temp/615e5631-1155-478e-93e8-8e5cc51fb88e.sh: line 1: /home/github-runner/actions-runner-new/_work/_actions/pylot-tech/actions_checkout/v1/clone.sh: No such file or directory