Protect repository branches ignores passed arguments
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### Summary
When protecting a new branch, the parameters for push access level & merge access level are ignored, and the default values are used.
### Steps to reproduce
Simply simply put your gitlab token, the gitlab base url and project id.
```
curl \
--request POST \
--header "Private-Token: ${GITLAB_TOKEN}" \
${GITLAB_URL}/api/v4/projects/${PROJECT_ID}/protected_branches?name=*-stable&push_access_level=30&merge_access_level=30
```
This request is directly taken from the CE documentation.
https://docs.gitlab.com/ce/api/protected_branches.html#protect-repository-branches
### Example Project
Version: 11.0.4 gitlab-ce@edb037cbc85225261e8ede5455be4aad771ba3bb
### What is the current *bug* behavior?
```
{"name":"*-stable","push_access_levels":[{"access_level":40,"access_level_description":"Maintainers"}],"merge_access_levels":[{"access_level":40,"access_level_description":"Maintainers"}]}
```
### What is the expected *correct* behavior?
Push & Merge level should be set to 30.
issue