Migrate PDCM Admin to use Postgres instead of H2

[mauroz77]

Description

Currently, the PDCM Admin service uses an H2 database, which we ourselves provide as a service in k8.
We could benefit from using instead the Postgres database that is already in place for the ETL. Some of the benefits are:

• Less admin load
• Backup of data
• I can add functionality to the Admin service by easily fetching data from the ETL database

Acceptance criteria

• PDCM API working connected to Postgres

[mauroz77]

@zperova done