Import OpenAPI API to Api Management

### Issue Details
Importing an api (services/api) to api management using _openapi-link_ will result in some of properties set on the template being ignored, e.g. ServiceUrl but not others e.g. API Prefix

### Repro steps (*if necessary, delete otherwise*)
1. Delete Echo API
1. Upload EchoAPI.openapi.yaml to blob storage (rename attachment)
2. Deploy template.json (rename attachment)

**Expected**

Echo API with a Service Url of: https://bobthebuilder.com/Calculation/v1

**Actual**

Echo API with a Service Url of: https://emeadev01.azure-api.net/echo

[template.txt](https://github.com/Azure/azure-quickstart-templates/files/3325776/template.txt)
[EchoAPI.openapi.txt](https://github.com/Azure/azure-quickstart-templates/files/3325780/EchoAPI.openapi.txt)

Start by reviewing template.txt and EchoAPI.openapi.txt, then reproduce the deployment using the listed blob-storage and template steps. Compare the ServiceUrl and API Prefix values defined in the template with those applied to the imported Echo API. Done means the deployed API has the expected ServiceUrl of https://bobthebuilder.com/Calculation/v1 without regressing the other properties.

Written by the indexing model from the issue text.