FIX #41 Azure Spring App tier should be "Standard"

[dbroeglin]

Purpose

Fix #41 by using "Standard" as Azure Spring Apps tier.

Does this introduce a breaking change?

[ ] Yes
[x] No

Pull Request Type

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

How to Test

azd init -t https://github.com/dbroeglin/app-templates-java-openai-springapps.git -b patch-1-fix-4-wrong-azure-spring-apps-tier
azd up

What to Check

Deployment should succeed.