26294: Accelerator Pipeline Adjustments

[oZakari]

Overview/Summary

General fixes and adjustments after testing with ALZ PowerShell Module.0.1.3

This PR fixes/adds/changes/removes

1. Related to AB#26294
2. Moved resource group deployment scripts values to GitHub Action environment variables to reduce amount of spots end-user needs to modify.
3. Fixing workflow path trigger reference to point to vwan param file instead of hub param file.
4. Added condition to check for existing custom module bicep files prior to attempting to run the bicep build action.

Breaking Changes

1. No breaking changes for ALZ PWSH module as no file paths have been changed.

Testing Evidence

Resource Group Deployment Changes

PR-1 Workflow changes

As part of this Pull Request I have

• Read the Contribution Guide and ensured this PR is compliant with the guide
• Ensured the resource API versions in .bicep file/s I am adding/editing are using the latest API version possible
• Checked for duplicate Pull Requests
• Associated it with relevant GitHub Issues
• (ALZ Bicep Core Team Only) Associated it with relevant ADO Items
• Ensured my code/branch is up-to-date with the latest changes in the main branch
• Performed testing and provided evidence.
• Updated one or more of the following tests (if required)
  • Unit
  • Linting
  • E2E (End-To-End)
  • ValidateAzCloud (Base validation in Azure Cloud)
  • ValidateMcCloud (Base validation in Azure China Cloud)
• Updated relevant and associated documentation (e.g. Contribution Guide, Module READMEs, Wiki Docs etc.)
• If relevant, created or updated Code Tours here