Multi-Tenant Tutorial: add redirect-uris in xs-security.json to fix 'Call the Service via Approuter'

[JenniferStamm]

Describe the bug
login callback uri wasn't built correctly.

To Reproduce
Follow the tutorial up to step 'Call the Service via Approuter'. The call will fail and you'll find the misconfigured callback url in the browser's dev tool console.

Expected behavior
No authentication/authorization issues.

Used Versions:

• node version via node -v: v18.15.0
• npm version via npm -v: 9.5.0
• SAP Cloud SDK version you used as dependency: does not apply, because the issue was with @sap/approuter and XSUAA
• @sap/approuter": "14.3.0"

Code Examples
Updating XSUAA xs-security.json with redirect-uri property fixed the issue.

Additional context
Following the contributing guidelines, I'd rather discuss the change before submitting a PR. It was an educated guess based on previous experience with XSUAA's xs-security.json. I don't know why we needed that property to get it working and whether it can be safely added for everyone.