Skip setup-python for arm64 Linux builds (#26497)
## Problem
The setup-python action does not support AzureLinux 3.0.20251030 for
arm64 architecture, causing workflow failures.
## Solution
Skip the setup-python step for arm64 builds since Python is already
available in the Docker containers used for those builds.
## Error Details
```
Version 3.x was not found in the local cache
(node:4478) [DEP0040] DeprecationWarning: The `punycode` module is deprecated. Please use a userland alternative instead.
(Use `node --trace-deprecation ...` to show where the warning was created)
Error: The version '3.x' with architecture 'arm64' was not found for azurelinux 3.0.20251030 undefined.
The list of all available versions can be found here: https://raw.githubusercontent.com/actions/python-versions/main/versions-manifest.json
```
