ci: add free-disk-space cleanup to test-e2e-podman job (#3557)

All sibling E2E jobs free disk before running; test-e2e-podman was
the only exception. It installs podman (large), so disk pressure is
more likely here than anywhere else.

Author: Ankitsinghsisodya

.github/workflows/functions.yaml

@@ -272,6 +272,14 @@ jobs:
       - uses: actions/checkout@v4
       - uses: knative/actions/setup-go@main
 
+      - uses: endersonmenezes/free-disk-space@v3
+        with:
+          remove_android: true
+          remove_dotnet: true
+          remove_haskell: true
+          remove_swap: true
+          rm_cmd: "rmz" # Faster than rm
+
       - name: Start Podman
         run: sudo apt update && sudo apt install -y podman && podman system service --time=0 &