[Bug][api] connection config test api changed upstream 404 error to 400

[leric]

Search before asking

• I had searched in the issues and found no similar issues.

What happened

Connection config test api used to report user friendly error message in release-0.20, e.g. a suggestion for correct url for 404 error, wrong user name and password for 401 error.
After update to 0.21 it returns raw error message from upstream, and status code become 400, even upstream error is 404 or 401.

v0.20

v0.21

What do you expect to happen

Same behavior as release-0.20

How to reproduce

Test a invalid connection options with plugin connection test api (invalid endpoint):

curl -X 'POST' \
  'http://localhost:4000/plugins/jira/test' \
  -H 'accept: application/json' \
  -H 'Content-Type: application/json' \
  -d '{
  "authMethod": "BasicAuth",
  "endpoint": "https://merico.atlassian.net/st",
  "password": "string",
  "proxy": "",
  "rateLimitPerHour": 11110,
  "username": "lianghui.zhang@merico.dev"
}'

Anything else

No response

Version

v0.21

Are you willing to submit PR?

• Yes I am willing to submit a PR!

Code of Conduct

• I agree to follow this project's Code of Conduct