Update codeowners for ess_billing

Author: lalit-satapathy

.github/CODEOWNERS

@@ -212,7 +212,7 @@
 /packages/entro @elastic/security-service-integrations
 /packages/envoyproxy @elastic/obs-infraobs-integrations
 /packages/eset_protect @elastic/security-service-integrations
-/packages/ess_billing @elastic/customer-architects
+/packages/ess_billing @elastic/customer-architects @elastic/obs-infraobs-integrations
 /packages/etcd @elastic/obs-infraobs-integrations
 /packages/extrahop @elastic/security-service-integrations
 /packages/f5_bigip @elastic/security-service-integrations