Revert "gha: ci-on-push: Adapt chained jobs to workflow_run"

This reverts commit 7855b43062.

Unfortunately we have to revert the PRs related to the switch done to
using `workflow_run` instead of `pull_request_target`.  The reason for
that being that we can only mark jobs as required if they are targetting
PRs.

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

.github/workflows/run-k8s-tests-on-aks.yaml

@@ -2,10 +2,6 @@ name: CI | Run kubernetes tests on AKS
 on:
   workflow_call:
     inputs:
-      checkout-ref:
-        required: false
-        type: string
-        default: ${{ github.sha }}
       registry:
         required: true
         type: string
@@ -34,7 +30,7 @@ jobs:
 
       - uses: actions/checkout@v3
         with:
-          ref: ${{ inputs.checkout-ref }}
+          ref: ${{ github.event.pull_request.head.sha }}
       - name: Install `bats`
         run: |
           sudo apt-get update