[pushmsix] Move app configuration out of init_worker.sh

We currently manage app-specific settings, such as RELEASE_ROLLOUT_PERCENTAGE, BETA_APPLICATION_ID, and RELEASE_APPLICATION_ID, directly within the init_worker.sh file. As we introduce new applications, we continue adding more entries, deviating from the purpose of this file.

We should consider a different approach for handling these settings. Potential solutions include:

• From Task Payload:
  Pass application-specific configurations through the task payload, keeping the logic inside pushmsix simpler, and making the requesting app more explicit on what's being pushed.

• Constants/Configuration File:
  Store all app-specific constants in a dedicated configuration file (similar to existing patterns in beetmover, iscript, etc). This file would serve as a centralized reference point, making updates and additions easier.

Open Questions:

• Which approach integrates best with our existing deployment and operational workflows?
• Are there additional options/strategies for handling these settings?

Start by reading init_worker.sh and reviewing the existing configuration patterns in beetmover and iscript. Compare the task-payload and dedicated-configuration-file options against deployment and operational workflows, then confirm the chosen approach keeps app-specific settings out of init_worker.sh while preserving current behavior.