Comment block adds code oddly when new line is added

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### How are you using the lua-language-server?

Visual Studio Code Extension (sumneko.lua)

### Which OS are you using?

Windows

### What is the issue affecting?

Completion

### Expected Behaviour

Nothing special happens when adding a new line to the end of a comment block.

### Actual Behaviour

The end of the comment block is duplicated.

### Reproduction steps

In a new X.lua file add the below as the only content.

```
--[[
Can teleport a player to near a target. Handles vehicles, finding valid placements and checking walkable paths based on settings.

HERE

end of comment
--]]

```

At the end of the word `HERE` add a new line by pressing enter and see the end of the comment block below it duplicated.

It produces the below.
```
--[[
Can teleport a player to near a target. Handles vehicles, finding valid placements and checking walkable paths based on settings.

HERE

end of comment
--]]

end of comment
--]]
```

### Additional Notes

https://github.com/LuaLS/lua-language-server/assets/40836017/3b1e6ddc-7ac0-4184-9e25-c644b462d92e

### Log File

_No response_

Reproduce the completion behavior in Visual Studio Code using a new X.lua file containing the reported block comment, then inspect the Lua language-server completion path for edits triggered by Enter inside a comment block. Done means pressing Enter after `HERE` no longer duplicates the trailing comment text and `--]]` terminator.

Written by the indexing model from the issue text.