ci: Cover more container posibilities

Add more conditions to the image prepare process.
This allows us to test the prebuilt images for both
Fedora and Ubuntu.

Run the weekly image on main branch with the
use of Fedora for the weekly runs.

Reported-at: https://issues.redhat.com/browse/FDP-149
Signed-off-by: Ales Musil <amusil@redhat.com>
Signed-off-by: Dumitru Ceara <dceara@redhat.com>

.github/workflows/test.yml

@@ -81,6 +81,15 @@ jobs:
       run: ./.ci/dpdk-build.sh
 
   prepare-container:
+    # This job has the following matrix, x: Job trigger, y: Branch
+    # (scheduled jobs run only on main):
+    # +-------+-------------------+-------------------+
+    # |       | Push/Pull request |     Scheduled     |
+    # +-------+-------------------+-------------------+
+    # |  main |  ghcr.io - Ubuntu | ghcr.io - Fedora  |
+    # +-------+-------------------+-------------------+
+    # | !main |  Builds - Ubuntu  | xxxxxxxxxxxxxxxxx |
+    # +-------+-------------------+-------------------+
     env:
       DEPENDENCIES: podman
     name: Prepare container
@@ -95,10 +104,25 @@ jobs:
       - name: Install dependencies
         run: sudo apt install -y ${{ env.DEPENDENCIES }}
 
+      - name: Choose image distro
+        if: github.event_name == 'push' || github.event_name == 'pull_request'
+        run: |
+          echo "IMAGE_DISTRO=ubuntu" >> $GITHUB_ENV
+
+      - name: Choose image distro
+        if: github.event_name == 'schedule'
+        run: |
+          echo "IMAGE_DISTRO=fedora" >> $GITHUB_ENV
+
       - name: Build container
-        run: make ubuntu
+        if: github.ref_name != 'main'
+        run: make ${{ env.IMAGE_DISTRO }}
         working-directory: utilities/containers
 
+      - name: Download container
+        if: github.ref_name == 'main'
+        run: podman pull ghcr.io/ovn-org/ovn-tests:${{ env.IMAGE_DISTRO }}
+
       - name: Export image
         run: podman save -o /tmp/image.tar ovn-org/ovn-tests