Export VITE_ environment variables in Start.sh

[egor-yudkin]

Purpose

This PR implements the change discussed in issue #2227

This change partially reverts commit 59e01c8 - it restores exporting of environment variables from azd env at the beginning of start.sh script. However, only variables that begin with VITE_ are being exported - they might be used by the frontend when the application is started locally.

Does this introduce a breaking change?

When developers merge from main and run the server, azd up, or azd deploy, will this produce an error?
If you're not sure, try it out on an old environment.

[ ] Yes
[x] No

Does this require changes to learn.microsoft.com docs?

This repository is referenced by this tutorial
which includes deployment, settings and usage instructions. If text or screenshot need to change in the tutorial,
check the box below and notify the tutorial author. A Microsoft employee can do this for you if you're an external contributor.

[ ] Yes
[x] No

Type of change

[ ] Bugfix
[x] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[ ] Other... Please describe:

Code quality checklist

See CONTRIBUTING.md for more details.

• The current tests all pass (python -m pytest).
• I added tests that prove my fix is effective or that my feature works
• I ran python -m pytest --cov to verify 100% coverage of added lines
• I ran python -m mypy to check for type errors
• I either used the pre-commit hooks or ran ruff and black manually on my code.

The start.sh script is not covered by tests.

[egor-yudkin]

@microsoft-github-policy-service agree company="Cleary Gottlieb Steen & Hamilton LLP"