feat: use the right url in approval emails sent to bundle admins

[amandazhuyilan]

Description

AAI-620: updates AAI portal links in approval emails to be environment-aware, defaulting to dev/staging URLs and allowing overrides via settings.

Changes

• Add ENVIRONMENT-based defaults for aai_portal_url in config.py
• Normalize portal URLs (strip trailing slashes) and validate unknown environments
• Add unit tests covering dev/staging defaults, override behavior, and invalid environment handling
• .env file would need to be set as

ENVIRONMENT=dev # default
# or
ENVIRONMENT=staging

Checklist

• I have commented my code, particularly in hard-to-understand areas
• I have added unit / integration tests that prove my fix is effective or that my feature works
• I have run all tests locally and they pass
• I have updated the documentation (if applicable)
• For any new secrets, I have updated the shared spreadsheet and the GitHub Secrets.

How to Test Manually (if necessary)

<Describe how reviewers can manually, if necessary, test the changes>

[marius-mather]

looks good to me