fix: return 403/404 error when stop events with mismatched scm host

[y-oksaku]

Context

SD API returns 500 error when user logged in mismatch SCM host stops events.

{
    "statusCode": 500,
    "error": "Internal Server Error",
    "message": "Pipeline's scmHost xxx.com does not match with user's scmHost yyy.com"
}

But in this case, API should return 403 error (or 404 when private pipeline).

Objective

Add error handling same as #2655

References

#2655

License

I confirm that this contribution is made under a BSD license and that I have the authority necessary to make this contribution on behalf of its copyright owner.

[coveralls]

coverage: 95.228% (+0.007%) from 95.221%
when pulling d175696 on sonic-screwdriver-cd:fix-status-code
into 3639673 on screwdriver-cd:master.