chore: update the CODEOWNERS file with new vertexai-team

PiperOrigin-RevId: 875322192

Author: vertex-sdk-bot

.github/CODEOWNERS

@@ -5,4 +5,5 @@
 # https://help.github.com/en/github/creating-cloning-and-archiving-repositories/about-code-owners#codeowners-syntax
 
 # The Vertex SDK dev team is the default owner for approving PRs.
-*                                      @googleapis/cloud-aiplatform-model-builder-sdk
+*                                      @googleapis/vertexai-team
+