Fix approvers auto assign list (open-telemetry#39203)

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#### Description

Fixes the list to reflect
https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/main/README.md

(reverts
open-telemetry#37857
and leftover of
open-telemetry#39121)

Signed-off-by: ChrsMark <[email protected]>

Author: ChrsMark

.github/auto_assign.yml

@@ -11,13 +11,13 @@ useAssigneeGroups: true
 assigneeGroups:
   approvers_maintainers:
     # Approvers
-    # - ChrsMark on leave
+    - ArthurSens
+    - ChrsMark
     - crobert-1
     # - dashpole on leave
     - dehaansa
     - edmocosta
     - mwear
-    - songy23
     - fatsheep9146
     # Maintainers
     - andrzej-stencel
@@ -30,6 +30,7 @@ assigneeGroups:
     - jpkrohling
     - MovieStoreGuy
     - mx-psi
+    - songy23
     - TylerHelmuth
 
 # A number of assignees added to the pull request