* Fix#9189 - API Allow only specific Colums to be updated on Issue (#9539)
* dont insert "-1" in any case to issue.poster_id
* Make sure API cant override importand fields
* code format
* add Test for IssueEdit
* load milestone and return it on IssueEdit via API
* extend Test for TestAPIEditIssue
* fix TEST
* make sure Poster is loaded
* keep code format on backport as it is