Revert "ci(Mergify): configuration update (#12599)" (#12642)

This reverts commit 184518c2fa.

.github/CODEOWNERS

@@ -59,4 +59,3 @@
 /README.md                       @williamfalcon @edenlightning @borda
 /setup.py                        @williamfalcon @borda
 /pytorch_lightning/__about__.py  @williamfalcon @borda
-/.github/mergify.yml             @williamfalcon @borda

.github/mergify.yml

@@ -68,29 +68,3 @@ pull_request_rules:
       request_reviews:
         teams:
           - "@PyTorchLightning/core-lightning"
-
-  - name: Grid.ai employee approval
-    conditions:
-      - or:
-        - approved-reviews-by=awaelchli
-        - approved-reviews-by=Borda
-        - approved-reviews-by=carmocca
-        - approved-reviews-by=edenlightning
-        - approved-reviews-by=ethanwharris
-        - approved-reviews-by=kaushikb11
-        - approved-reviews-by=krshrimali
-        - approved-reviews-by=rohitgr7
-        - approved-reviews-by=tchaton
-        - approved-reviews-by=williamFalcon
-    actions:
-      post_check:
-        title: |
-          {% if check_succeed %}
-          This PR has Grid.ai approval.
-          {% else %}
-          This PR is waiting for approval from a Grid.ai team member.
-          {% endif %}
-        summary: |
-          {% if not check_succeed %}
-          Each pull request must be approved by at least one Grid.ai team member.
-          {% endif %}