Revert "ci: gha: Remove ok-to-test label on every push"

This reverts commit 2ee3470627.

This is mostly redundant given we already have workflow approval for external
contributors.

Signed-off-by: Aurélien Bombo <abombo@microsoft.com>

.github/workflows/validate-ok-to-test.yml

@@ -1,30 +0,0 @@
-name: Validate ok-to-test label
-
-on:
-  pull_request_target:
-    types: [synchronize]
-
-jobs:
-  remove-label-if-needed:
-    runs-on: ubuntu-22.04
-    permissions:
-      # SAFETY: Only enough to modify labels.
-      issues: write
-    steps:
-      - name: Remove ok-to-test label on push
-        env:
-          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-          PR_NUMBER: ${{ github.event.pull_request.number }}
-          AUTHOR: ${{ github.event.pull_request.user.login }}
-          OWNER: ${{ github.repository.owner.login }}
-          REPO: ${{ github.event.repository.name }}
-        run: |
-          permission="$(gh api "repos/${OWNER}/${REPO}/collaborators/${AUTHOR}/permission" --jq '.permission')"
-          echo "User ${AUTHOR} has permission '${permission}'"
-
-          if [[ "${permission}" != "write" && "${permission}" != "admin" ]]; then
-            echo "Removing 'ok-to-test' label"
-            gh pr edit "${PR_NUMBER}" --repo "${OWNER}/${REPO}" --remove-label "ok-to-test"
-          else
-            echo "User has label permission - skipping removal"
-          fi