google-cloud-bigtable system tests are failing with ResourceExhausted #18162

See the failure below where google-cloud-bigtable system tests are hitting a quota limit.

google.api_core.exceptions.ResourceExhausted: 429 Quota exceeded for quota metric 'Instance and cluster metadata write requests' and limit 'Instance and cluster metadata write requests per day' of service 'bigtableadmin.googleapis.com'

Regrettably, the quota limit is a system limit. As per https://docs.cloud.google.com/bigtable/quotas, System limits are fixed values that can't be changed.

In PR #18148, we temporarily disabled system tests for google-cloud-bigtable. This bug tracks restoring the system tests. In the meantime, we still have emulator tests running.