rds: changing to factory instantiation

[alyssawilk]

Risk Level: low Testing: updated tests Docs Changes: n/a Release Notes: n/a https://github.com/envoyproxy/envoy-mobile/issues/176

[repokitteh-read-only[bot]]

As a reminder, PRs marked as draft will not be automatically assigned reviewers, or be handled by maintainer-oncall triage.

Please mark your PR as ready when you want it to be reviewed!

:cat:

Caused by: https://github.com/envoyproxy/envoy/pull/34203 was opened by alyssawilk.

see: more, trace.

[alyssawilk]

/retest