fix: 400 error editing posts and comment

[DmytroAlipov]

This is a backport from the master and and this PR

Description

When trying to edit a post or comment, an error 400 occurred. Provided that the user is a course instructor or staff, and simultaneously the author of the post/comment.

The issue is the presence of the editReasonCode parameter in the request.

This parameter is expected only if the editor is not the author of the post/comment, and is a staff or instructor.

After the fixes, everything works correctly.

Merge Checklist

• [ ] If your update includes visual changes, have they been reviewed by a designer? Send them a link to the Sandbox, if applicable.
• [ ] Is there adequate test coverage for your changes?

Post-merge Checklist

• [ ] Deploy the changes to prod after verifying on stage or ask @openedx/edx-infinity to do it.
• [ ] 🎉 🙌 Celebrate! Thanks for your contribution.

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[codecov[bot]]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.01 :tada:

Comparison is base (7dfbd44) 85.06% compared to head (2563209) 85.07%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## open-release/olive.master #534 +/- ## ============================================================= + Coverage 85.06% 85.07% +0.01% ============================================================= Files 134 134 Lines 2678 2680 +2 Branches 741 743 +2 ============================================================= + Hits 2278 2280 +2 Misses 378 378 Partials 22 22 ``` | [Impacted Files](https://app.codecov.io/gh/openedx/frontend-app-discussions/pull/534?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=openedx) | Coverage Δ | | |---|---|---| | [src/discussions/comments/comment/CommentEditor.jsx](https://app.codecov.io/gh/openedx/frontend-app-discussions/pull/534?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=openedx#diff-c3JjL2Rpc2N1c3Npb25zL2NvbW1lbnRzL2NvbW1lbnQvQ29tbWVudEVkaXRvci5qc3g=) | `97.50% <100.00%> (+0.06%)` | :arrow_up: | | [src/discussions/posts/PostsList.jsx](https://app.codecov.io/gh/openedx/frontend-app-discussions/pull/534?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=openedx#diff-c3JjL2Rpc2N1c3Npb25zL3Bvc3RzL1Bvc3RzTGlzdC5qc3g=) | `97.29% <100.00%> (ø)` | | | [src/discussions/posts/post-editor/PostEditor.jsx](https://app.codecov.io/gh/openedx/frontend-app-discussions/pull/534?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=openedx#diff-c3JjL2Rpc2N1c3Npb25zL3Bvc3RzL3Bvc3QtZWRpdG9yL1Bvc3RFZGl0b3IuanN4) | `85.29% <100.00%> (+0.14%)` | :arrow_up: |

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[mphilbrick211]

Hi @asadazam93! Would you mind reviewing/merging? Thanks!

[awais-ansari]

@DmytroAlipov Thanks for your contribution. The Team will review your PR very soon and let you know about it.

[openedx-webhooks]

@DmytroAlipov 🎉 Your pull request was merged! Please take a moment to answer a two question survey so we can improve your experience in the future.