Fix issues reordering fields description

What does this MR do?

Related to #246162 (closed)

This issue raised that the behaviour of the GraphQL mutation issueMoveList is not matching the fields description and @engwan noticed that the description is actually incorrect, along with the ones for the REST API endpoint:

So it looks like our GraphQL and REST API descriptions for these params are actually incorrect:

description: 'ID of issue before which the current issue will be positioned at'
description: 'ID of issue after which the current issue will be positioned at'

| `move_after_id` | integer | no | The ID of a project's issue to move this issue after |
| `move_before_id` | integer | no | The ID of a project's issue to move this issue before |

If you look at the docs for Epics, it is correct:

| `move_before_id` | integer        | no       | The global ID of a sibling epic that should be placed before the child epic.                                       >|
| `move_after_id`  | integer        | no       | The global ID of a sibling epic that should be placed after the child epic.                                        

Link to REST API docs: https://docs.gitlab.com/ee/api/issues.html#reorder-an-issue

Related issues

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