github-actions: updatecli bump for specific branches (#8466)

Author: v1v

.github/workflows/bump-vm-images.yml

@@ -41,6 +41,13 @@ jobs:
       matrix: ${{ fromJson(needs.filter.outputs.matrix) }}
     steps:
       - uses: actions/checkout@v4
+        with:
+          # NOTE: as long as the updatecli bump differs between branches, we need to
+          # checkout the branch that we are going to bump that we are going to bump
+          # this is needed to ensure that the updatecli bump is done against the correct updatecli
+          # pipeline. For instance, https://github.com/elastic/elastic-agent/pull/8035 was not
+          # backported to the short lived branches.
+          ref: ${{ matrix.branch }}
 
       - uses: elastic/oblt-actions/updatecli/run@v1
         with:
@@ -54,4 +61,4 @@ jobs:
         with:
           bot-token: ${{ secrets.SLACK_BOT_TOKEN }}
           channel-id: "#ingest-notifications"
-          message: ":traffic_cone: updatecli failed for `${{ github.repository }}@${{ github.ref_name }}`, @robots-ci please look what's going on <${{ env.JOB_URL }}|here>"
+          message: ":traffic_cone: updatecli failed for `${{ github.repository }}@${{ github.ref_name }}`[${{ matrix.branch }}], @robots-ci please look what's going on <${{ env.JOB_URL }}|here>"