Unauthorized Error Due to Missing PagerDuty Backend Plugin in Backstage Showcase

Test case Failed : https://issues.redhat.com/browse/RHIDP-666

RC: Backstage showcase missing PagerDuty backend plugin. As a result, receiving unauthorized error.

As per the migration doc, PagerDuty backend plugin is required.

[-https://pagerduty.github.io/backstage-plugin-docs/migration/-]

new migration doc link : https://pagerduty.github.io/backstage-plugin-docs/migration/backend-system-migration/ 

Steps To reproduce:

1. Create pagerduty service and integration.
2. Update Catalog.yaml : https://github.com/subhashkhileri/pagerdutytest/blob/main/catalog-info.yaml 
3. Generate Generall access key token.
4. Enable pagerduty dynamic plugin :

- package: ./dynamic-plugins/dist/pagerduty-backstage-plugin
  disabled: false 

1. Update app-config.yaml

pagerDuty:
  apiToken: ${PAGERDUTY_TOKEN}