chore(tests): Cleanup test matrix

There is no point of having a more complex series of jobs.
This puts all the manifests testing cases into one kind of
pipeline, simplifying debugging.

Signed-off-by: Jean-Philippe Evrard <open-source@a.spamming.party>

.github/workflows/on-branch-push-and-prs.yaml

@@ -73,8 +73,8 @@ jobs:
   # - Test manifests changes (obviously), ensuring they don't break existing clusters
   # - Ensure manifests work with the latest versions even with no manifest change
   #     (compared to helm charts, manifests cannot easily template changes based on versions)
+  # - Test some features are working as expected.
   # Helm charts are _trailing_ releases, while manifests are done during development.
-  # This test uses the "command" reboot-method.
   e2e-manifests:
     name: End-to-End test with kured with code and manifests from HEAD
     runs-on: ubuntu-latest
@@ -82,39 +82,14 @@ jobs:
       fail-fast: false
       matrix:
         testname:
-          - "TestE2EWithCommand"
-          - "TestE2EWithSignal"
-          - "TestE2EConcurrentWithCommand"
-          - "TestE2EConcurrentWithSignal"
-        kubernetes_version:
-          - "previous"
-          - "current"
-    steps:
-      - name: Harden Runner
-        uses: step-security/harden-runner@9af89fc71515a100421586dfdb3dc9c984fbf411 # v2.19.4
-        with:
-          egress-policy: audit
-
-      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
-
-      - uses: jdx/mise-action@dba19683ed58901619b14f395a24841710cb4925 # v4.1.0
-        with:
-          version: 2026.6.1
-
-      - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@d7f5e7f509e45cec5c76c4d5afdd7de93d0b3df5 # v4.1.0
-
-      - name: Run specific e2e tests
-        run: make e2e-test ARGS="-run ^${{ matrix.testname }}/${{ matrix.kubernetes_version }}"
-
-
-  e2e-tests-singleversion:
-    name: End-to-End test targetting a single version of kubernetes
-    runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        testname:
+          - "TestE2EWithCommand/current"
+          - "TestE2EWithCommand/previous"
+          - "TestE2EWithSignal/current"
+          - "TestE2EWithSignal/previous"
+          - "TestE2EConcurrentWithCommand/current"
+          - "TestE2EConcurrentWithCommand/previous"
+          - "TestE2EConcurrentWithSignal/current"
+          - "TestE2EConcurrentWithSignal/previous"
           - "TestCordonningIsKept/concurrency1"
           - "TestCordonningIsKept/concurrency2"
           - "TestE2EBlocker/podblocker"