Remove stewart-yu as an approver/reviewer (#16750)

Set stewart-yu to emeritus approver

Newline comment

OWNERS

@@ -9,6 +9,8 @@ approvers:
 emeritus_approvers:
 - chenopis
 - jaredbhatti
+# stewart-yu, you're welcome to return when you're ready to resume PR wrangling
+- stewart-yu 
 
 labels:
 - sig/docs

OWNERS_ALIASES

@@ -51,7 +51,6 @@ aliases:
     - ryanmcginnis
     - simplytunde
     - steveperry-53
-    - stewart-yu
     - tengqm
     - tfogo
     - xiangpengzhao
@@ -60,7 +59,6 @@ aliases:
   sig-docs-en-reviews: # PR reviews for English content
     - rajakavitha1
     - sftim
-    - stewart-yu
   sig-docs-es-owners: # Admins for Spanish content
     - raelga
     - alexbrand