app_build_command is not actually run for a Python SWA

**Describe the bug**

I ran the following workflow file for my Python-generated SWA:

https://github.com/pamelafox/pamelafox-site/actions/runs/4157879523/workflow

With this configuration:
```
app_build_command: "python3 freeze.py"
```

In the workflow log, it claims:

"Oryx will build app with the following custom override command: python3 freeze.py"

However, there is no evidence that Oryx ran that command in the logs.
Instead, I had to add this Oryx env variable:

```
POST_BUILD_COMMAND: "python3 freeze.py"
```

You can see that in this working workflow file:

https://github.com/pamelafox/pamelafox-site/actions/runs/4157913512/workflow

**To Reproduce**

Steps to reproduce the behavior:

1. Check out my repo (https://github.com/pamelafox/pamelafox-site/) at commit 7dbc897d1f7fc4db8ad61e13237ae3a31d8ea00f
2. Provision resources using Bicep file
3. Setup credentials for CI
4. Watch CI fail

**Expected behavior**

I expected it to either run app_build_command or make it clear somewhere that it won't be run for Python apps.