chore: update owners

This updates the owners (and aliases) to reduce unecessary notifcations
and review requests.

Signed-off-by: Richard Case <richard.case@outlook.com>

OWNERS

@@ -1,16 +1,13 @@
 # See the OWNERS docs: <https://git.k8s.io/community/contributors/guide/owners.md>
 
 approvers:
-  - sig-cluster-lifecycle-leads
-  - cluster-api-admins
   - cluster-api-aws-admins
   - cluster-api-aws-maintainers
 
 reviewers:
   - cluster-api-aws-admins
   - cluster-api-aws-maintainers
   - cluster-api-aws-reviewers
-  - cluster-api-maintainers
 
 emeritus_approvers:
   - AverageMarcus

OWNERS_ALIASES

@@ -1,22 +1,6 @@
 # See the OWNERS docs: <https://github.com/kubernetes/community/blob/master/contributors/guide/owners.md>
 
 aliases:
-  sig-cluster-lifecycle-leads:
-    - fabriziopandini
-    - justinsb
-    - neolit123
-    - vincepri
-  cluster-api-admins:
-    - fabriziopandini
-    - sbueringer
-    - vincepri
-  cluster-api-maintainers:
-    - chrischdi
-    - enxebre
-    - fabriziopandini
-    - killianmuldoon
-    - sbueringer
-    - vincepri
   cluster-api-aws-admins:
     - richardcase
   cluster-api-aws-maintainers: