PMM Server can support up to 100 AWS RDS instances. When enhanced monitoring is configured, rds_exporter will crash when attempting to add greater than 100 AWS RDS instances.
RDS exporter calls cloudwatch's method FilterLogEvents with a parameter LogStreamNames,
which cannot be longer than 100 elements:
QA: no need to have extensive testing on 100+ RDS. Making sure we don't have regression is good enough