POI returns no route for not covered areas (#1960)

[xieofxie]

Purpose

What is the context of this pull request? Why is it being done?

Close #1960

Changes

Are there any changes that need to be called out as significant or particularly difficult to grasp? (Include illustrative screenshots for context if applicable.)

Return no route for BadRequest. This behavior (return 400 for not covered areas) is not guaranteed stable in azure map.

Tests

Is this covered by existing tests or new ones? If no, why not?

user: find a coffee shop in tokyo
user: [input current(tokyo) and select coffee shop]
bot: It seems like something went wrong. (before)
bot: Sorry, I didn't find any route. (now)

Feature Plan

Are there any remaining steps or dependencies before this issue can be fully resolved? If so, describe and link to any relevant pull requests or issues.

Checklist

General

• I have commented my code, particularly in hard-to-understand areas
• I have added or updated the appropriate tests
• I have updated related documentation

Bots

• I have validated that new and updated responses use appropriate Speak and InputHint properties to ensure a high-quality speech-first experience
• I have replicated language model changes across the English, French, Italian, German, Spanish, and Chinese .lu files and validated that deployment is successful

Deployment Scripts

• I have replicated my changes in the Virtual Assistant Template and Sample projects
• I have replicated my changes in the Skill Template and Sample projects

[ryanisgrig]

Can you make this PR against the next branch?

[xieofxie]

OK, changed