Update codeowners to reflect code ownership

Author: shivanee-p

.github/CODEOWNERS

@@ -14,6 +14,4 @@
 /handwritten/firestore @googleapis/firestore-team
 /handwritten/spanner @googleapis/spanner-team
 /handwritten/bigquery-storage @googleapis/bigquery-team
-/handwritten/pubsub @googleapis/pubsub-team
-/handwritten/bigtable @googleapis/bigtable-team
 /core/packages/google-auth-library-nodejs @googleapis/aion-team