Hierarchy widget: need to refresh issue to create a work item after turning on confidentiality
### Summary
Doesn't look like we're updating Apollo Cache on the sidebar, or we're using a different cache for hierarchy, but we're not passing an updated parent confidentiality when creating a task.

### Steps to reproduce
1. With `:work_items_hierarchy` on, create a public issue.
2. Make it confidential
3. Click "Add a task" from the hierarchy widget.
4. Add a title, click "Create task"
### Example Project
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### What is the current *bug* behavior?
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### What is the expected *correct* behavior?
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### Relevant logs and/or screenshots
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### Output of checks
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#### Results of GitLab environment info
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<details>
<summary>Expand for output related to GitLab environment info</summary>
<pre>
(For installations with omnibus-gitlab package run and paste the output of:
`sudo gitlab-rake gitlab:env:info`)
(For installations from source run and paste the output of:
`sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production`)
</pre>
</details>
#### Results of GitLab application Check
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<details>
<summary>Expand for output related to the GitLab application check</summary>
<pre>
(For installations with omnibus-gitlab package run and paste the output of:
`sudo gitlab-rake gitlab:check SANITIZE=true`)
(For installations from source run and paste the output of:
`sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true`)
(we will only investigate if the tests are passing)
</pre>
</details>
### Possible fixes
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issue