Show 'Delete' button to developers in Wiki

What does this MR do?

At the moment, only maintainers can delete wiki pages through the UI. Nevertheless, other roles, like developers can do so directly through Git. In this MR, we're aligning that behavior and we're allowing users with the developers role to delete wiki pages through the UI.

Does this MR meet the acceptance criteria?

Conformity

• I have included changelog trailers, or none are needed. (Does this MR need a changelog?)
• I have properly separated EE content from FOSS, or this MR is FOSS only. (Where should EE code go?)
• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.
• This change is backwards compatible across updates, or this does not apply.

Related to #294048 (closed)