Replace service module with rest helper

[yulinscottkang]

Replace service module with rest helper in the following samples:

• https://samples.azuremaps.com/?sample=search-for-points-of-interest
• https://samples.azuremaps.com/?sample=route-to-a-destination
• https://samples.azuremaps.com/?sample=multiple-routes-by-mode-of-travel
• https://samples.azuremaps.com/?sample=simple-store-locator

These samples are referenced in the MS Learn tutorials, with a PR update (https://github.com/MicrosoftDocs/azure-docs-pr/pull/272435) to remove mentions of the service module.