Two definitions for local function variables

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

NeoVim

### Which OS are you using?

Linux

### What is the issue affecting?

Other

### Expected Behaviour

Using vim.lsp.buf.definition() to go to the definition of a local function variable (assigned with the `=` operator), should give only a single definition at the local variable name.

### Actual Behaviour

Using vim.lsp.buf.definition() to go to the definition of a local function variable (assigned with the `=` operator), gives two definitions on the same line. One is located at the variable name and the other is located at the beginning of the function key word.

### Reproduction steps

1. Create a lua file with the following content:
```lua
local m = function() print "hello world" end

m()
```
2. Move the cursor on the `m()` function call
3. Execute the neovim command `:lua vim.lsp.buf.definition()`

### Additional Notes

_No response_

### Log File

```
[DEBUG][2023-12-16 17:31:59] .../lua/vim/lsp.lua:1391 "LSP[lua_ls]" "client.request" 1 "textDocument/definition" { position = { character = 0, line = 2 }, textDocument = { uri = "file:///home/tobias/.config/nvim/test.lua" }} 147
[DEBUG][2023-12-16 17:31:59] .../vim/lsp/rpc.lua:284 "rpc.send" { id = 1559, jsonrpc = "2.0", method = "textDocument/definition", params = { position = { character = 0, line = 2 }, textDocument = { uri = "file:///home/tobias/.config/nvim/test.lua" } }}
[DEBUG][2023-12-16 17:31:59] .../vim/lsp/rpc.lua:387 "rpc.receive" { id = 1559, jsonrpc = "2.0", result = { { originSelectionRange = { ["end"] = { character = 1, line = 2 }, start = { character = 0, line = 2 } }, targetRange = { ["end"] = { character = 7, line = 0 }, start = { character = 6, line = 0 } }, targetSelectionRange = { ["end"] = { character = 7, line = 0 }, start = { character = 6, line = 0 } }, targetUri = "file:///home/tobias/.config/nvim/test.lua" }, { originSelectionRange = { ["end"] = { character = 1, line = 2 }, start = { character = 0, line = 2 } }, targetRange = { ["end"] = { character = 44, line = 0 }, start = { character = 10, line = 0 } }, targetSelectionRange = { ["end"] = { character = 44, line = 0 }, start = { character = 10, line = 0 } }, targetUri = "file:///home/tobias/.config/nvim/test.lua" } }}
[DEBUG][2023-12-16 17:32:02] .../lua/vim/lsp.lua:1391 "LSP[lua_ls]" "client.request" 1 "textDocument/codeLens" { textDocument = { uri = "file:///home/tobias/.config/nvim/test.lua" }} 147
[DEBUG][2023-12-16 17:32:02] .../vim/lsp/rpc.lua:284 "rpc.send" { id = 1560, jsonrpc = "2.0", method = "textDocument/codeLens", params = { textDocument = { uri = "file:///home/tobias/.config/nvim/test.lua" } }}
[DEBUG][2023-12-16 17:32:02] .../vim/lsp/rpc.lua:387 "rpc.receive" { id = 1560, jsonrpc = "2.0"}
[DEBUG][2023-12-16 17:32:02] .../lua/vim/lsp.lua:1391 "LSP[lua_ls]" "client.request" 1 "textDocument/documentHighlight" { position = { character = 0, line = 2 }, textDocument = { uri = "file:///home/tobias/.config/nvim/test.lua" }} 147
[DEBUG][2023-12-16 17:32:02] .../vim/lsp/rpc.lua:284 "rpc.send" { id = 1561, jsonrpc = "2.0", method = "textDocument/documentHighlight", params = { position = { character = 0, line = 2 }, textDocument = { uri = "file:///home/tobias/.config/nvim/test.lua" } }}
[DEBUG][2023-12-16 17:32:02] .../vim/lsp/rpc.lua:387 "rpc.receive" { id = 1561, jsonrpc = "2.0", result = { { kind = 3, range = { ["end"] = { character = 7, line = 0 }, start = { character = 6, line = 0 } } }, { kind = 2, range = { ["end"] = { character = 1, line = 2 }, start = { character = 0, line = 2 } } } }}
[TRACE][2023-12-16 17:32:02] ...lsp/handlers.lua:618 "default_handler" "textDocument/documentHighlight" { ctx = '{\n bufnr = 147,\n client_id = 1,\n method = "textDocument/documentHighlight",\n params = {\n position = {\n character = 0,\n line = 2\n },\n textDocument = {\n uri = "file:///home/tobias/.config/nvim/test.lua"\n }\n }\n}', result = { { kind = 3, range = { ["end"] = { character = 7, line = 0 }, start = { character = 6, line = 0 } } }, { kind = 2, range = { ["end"] = { character = 1, line = 2 }, start = { character = 0, line = 2 } } } }}

```

Start at the textDocument/definition entry point and reproduce the report with the Lua snippet in the issue using Neovim's vim.lsp.buf.definition(). Trace why the local function assignment produces both the variable name and function keyword ranges; done means the request returns only the local variable definition.

Written by the indexing model from the issue text.