@see annotaton duplicates documentation when using with @class

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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?

Annotations

### Expected Behaviour

I'm trying to add some `@see` tags to my `@class`

### Actual Behaviour

When hovering class in editor, displayed documentation is printed twice.

### Reproduction steps

Here is basic code sample. Hovering or typing `class1` causes issue with displayed documentation
```lua
--- some class dock
---
---@class C2
local class2 = {}

--- another class dock here
---
---@see C2
---@class C1
local class1 = {}

---@type C1
local class1_instance = class1
```

Start with the provided Lua reproduction in the issue and compare hover results for C1 with and without the @see C2 annotation. No repository file or test is named, so locate the annotation and class-documentation handling used by the language server, then verify that C1's documentation is displayed once while the @see reference remains available.

Written by the indexing model from the issue text.