Update CODEOWNERS (hazelcast#1252)

Resolves error:
<img width="1224" alt="image"
src="https://github.com/user-attachments/assets/25306914-f161-482f-82b0-ad6e53aed019">

The `cpp-client-team` doesn't exist, updated to the only user with
suitable permissions in the repository.

Note that [APIs does not have the required
permissions](https://github.com/orgs/hazelcast/teams/apis) to be
suitable, despite being a more sensible choice.

.github/CODEOWNERS

@@ -2,7 +2,5 @@
 # Each line is a file pattern followed by one or more owners.
 
 # These owners will be the default owners for everything in
-# the repo. Unless a later match takes precedence,
-# @ihsandemir and @sancar will be requested for
-# review when someone opens a pull request.
-*       @hazelcast/cpp-client-team
+# the repo.
+*       @ihsandemir