upgrade job needs to make use of pq username from secret not assume "forge"

[hardillb]

Current Behavior

Upgrade job runs the following SQL

    #!/bin/sh
    apk add --no-cache postgresql14-client
    psql -v ON_ERROR_STOP=1 -h {{ .Release.Name }}-postgresql -U postgres postgres <<-ESQL
    SELECT datname FROM pg_database WHERE datistemplate = false;
    SELECT 'CREATE DATABASE "ff-context"' WHERE NOT EXISTS (SELECT FROM pg_database WHERE datname = 'ff-context')\gexec
    GRANT ALL PRIVILEGES ON DATABASE "ff-context" TO "forge";
    ESQL

Expected Behavior

• We should allow context db name to be passed in as argument to the helm chart
• We should pick up the username for the context db from the pg secret

Steps To Reproduce

Install helm chart.

Environment

• FlowFuse version: 2.0.0
• Node.js version: 18
• npm version: 9
• Platform/OS: K8S
• Browser: NA