DBaaS: Internal server error after migration to 2.34.0

User impact:

User gets Internal server error in UI and cannot see DB clusters credentials

Steps to reproduce:

Start PMM < 2.34.0
Register two different kubernetes clusters
Create a DB cluster on both of them
Upgrade PMM to 2.34.0 or higher
Unregister both clusters in dbaas (with force option)
Run the migration script https://github.com/percona/pmm/blob/main/migrate-dbaas.py
Check DB clusters page (refresh few times)

Actual result:

Peek 2023-01-27 15-45.webm

Expected result:

No errors and credentials displayed

Workaround:

Details:

3.144.172.226.har