[Bug] Cannot Connect to OnPrem Azure DevOps server 2020 with token

Cannot Use Token with full permission to connect to OnPrem Azure DevOpos Server 2020 RTW

**To Reproduce**
azure-cli 2.15.0
core 2.15.0
telemetry 1.0.6
Extensions:
azure-devops 0.18.0

Python location 'C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\python.exe'
Python (Windows) 3.6.8 (tags/v3.6.8:3c6b436a57, Dec 23 2018, 23:31:17) [MSC v.1916 32 bit (Intel)]

Steps to reproduce the behavior:
1. login using az devops login --verbose --organization https://aztest/CollectionName
2. Enter Token:
3. Run command....
4. See error

**Expected behavior**
login sucessfull

**Screenshots**
If applicable, add screenshots to help explain your problem.

**Debug logs**
Add the output of the command running it with debug mode (--debug)
[ErrorLoginWithToken.txt](https://github.com/Azure/azure-devops-cli-extension/files/5566151/ErrorLoginWithToken.txt)

**Additional context**
connecting with RestAPI to the same server works ok
Clone from Server OK

首先，使用报告中的 Azure CLI 和扩展版本重现 `az devops login --verbose --organization https://aztest/CollectionName`，然后检查 ErrorLoginWithToken.txt 和屏幕截图以了解失败的详细信息。将令牌登录与报告中可正常工作的 REST API 和 clone 行为进行比较；当令牌登录能够成功连接到本地部署的 Azure DevOps Server 2020 实例时，即表示完成。

由索引模型根据 Issue 内容生成。