DEV: Always run all three qunit partitions, even with earlier failure (#16411)

Previously, if Core QUnit 1 failed, then QUnit 2/3 wouldn't even be attempted. When dealing with multiple failures, this can make the feedback cycle. Setting `if: always()` ensures that the steps run regardless of any earlier failures. This is the same approach we take in the linting workflow.

.github/workflows/tests.yml

@@ -235,16 +235,19 @@ jobs:
           sudo -E -u discourse -H yarn ember build --environment=test  -o /tmp/emberbuild
 
       - name: Core QUnit 1
+        if: ${{ always() }}
         working-directory: ./app/assets/javascripts/discourse
         run: sudo -E -u discourse -H yarn ember exam --path /tmp/emberbuild --split=3 --partition=1 --launch "${{ matrix.browser }}" --random
         timeout-minutes: 20
 
       - name: Core QUnit 2
+        if: ${{ always() }}
         working-directory: ./app/assets/javascripts/discourse
         run: sudo -E -u discourse -H yarn ember exam --path /tmp/emberbuild --split=3 --partition=2 --launch "${{ matrix.browser }}" --random
         timeout-minutes: 20
 
       - name: Core QUnit 3
+        if: ${{ always() }}
         working-directory: ./app/assets/javascripts/discourse
         run: sudo -E -u discourse -H yarn ember exam --path /tmp/emberbuild --split=3 --partition=3 --launch "${{ matrix.browser }}" --random
         timeout-minutes: 20