Specify number of Postgres Connections

[PaulWen]

To avoid connection exhaustion:

1. explicitly define the number of connections the Postgres DB should allow
2. limit the number of connections each AcaPy is allowed to open

[PaulWen]

Specifying Max number of connections a Postgres allows: https://stackoverflow.com/a/32584211

BcGov limits the number of connections one AcaPy can have with the Wallet DB to 5 in their PRD setup: https://github.com/bcgov/orgbook-configurations/blob/main/openshift/templates/agent/agent-deploy.bc.prod.param

[PaulWen]

https://github.com/My-DIGI-ID/aries-cloudagent-loadgenerator/commit/2f024eefa641f03a284ce0f997afd08858d77877