Remove SCL reviewers/approvers from OWNERS_ALIASES

To adequately leverage the SCL reviewers/approvers list in OWNERS_ALIASES,
we would need to add multiple OWNERS files in various directories.
Otherwise, the bot ends up suggesting reviewers and approvers from
other parent directories.

To avoid this complexity, simply remove the list of SCL reviewers/approvers
from OWNERS_ALIASES.

OWNERS_ALIASES

@@ -1,21 +1,4 @@
 aliases:
-  sig-cluster-lifecycle-kubeadm-approvers: # Approving changes to kubeadm documentation
-    - timothysc
-    - lukemarsden
-    - luxas
-    - fabriziopandini
-  sig-cluster-lifecycle-kubeadm-reviewers: # Reviewing kubeadm documentation
-    - timothysc
-    - lukemarsden
-    - luxas
-    - fabriziopandini
-    - kad
-    - xiangpengzhao
-    - stealthybox
-    - liztio
-    - chuckha
-    - detiber
-    - dixudx
   sig-docs-blog-owners: # Approvers for blog content
     - castrojo
     - kbarnard10