gha: Manually rebase PR atop of the target branch before testing

We're changing what's been done as part of ac939c458c, as we've
notcied issues using `github.event.pull_request.merge_commit_sha`.

Basically, whenever a force-push would happen, the reference of
merge_commit_sha wouldn't be updated, leading us to test PRs with the
old code. :-/

In order to get the rebase properly working, we need to ensure we pull
the hash of the commit as part of checkout action, and ensure
fetch-depth is set to 0.

Fixes: #7414

Signed-off-by: Fabiano Fidêncio <fabiano.fidencio@intel.com>

.github/workflows/move-issues-to-in-progress.yaml

@@ -40,7 +40,15 @@ jobs:
         if: ${{ !contains(github.event.pull_request.labels.*.name, 'force-skip-ci') }}
         uses: actions/checkout@v3
         with:
-          ref: ${{ github.event.pull_request.merge_commit_sha }}
+          ref: ${{ github.event.pull_request.head.sha }}
+          fetch-depth: 0
+
+      - name: Rebase atop of the latest target branch
+        if: ${{ !contains(github.event.pull_request.labels.*.name, 'force-skip-ci') }}
+        run: |
+          ./tests/git-helper.sh "rebase-atop-of-the-latest-target-branch"
+        env:
+          TARGET_BRANCH: ${{ github.event.pull_request.base.ref }}
 
       - name: Move issue to "In progress"
         if: ${{ !contains(github.event.pull_request.labels.*.name, 'force-skip-ci') }}