fix(kotlin): kotlin plugin messages and code maintain consistency (#3291)

### Description
I am the author of this
[PR](https://github.com/LazyVim/LazyVim/pull/2890).

While reviewing my own code and checking the LazyVim official website, I
noticed some inconsistencies 😓 , so I created a small PR to address
them:

### Changes
1.Each optional plugin has a comment message indicating that the plugin
is optional, but DAP does not (as shown in the image). Since the
official website already has an "optional" in title.
**I removed the comment messages regarding "optional" to avoid
confusion**.
<img width="300" alt="Screenshot 2024-05-23 at 10 31 38 PM"
src="https://github.com/LazyVim/LazyVim/assets/82575487/441979fc-20dd-4599-a91d-f27bc0841d79">


---

2. I changed the DAP to use local variables for DAP to maintain
consistency, even though both require statements reference the same
module.

lua/lazyvim/plugins/extras/lang/kotlin.lua

@@ -16,7 +16,7 @@ return {
   {
     "williamboman/mason.nvim",
     opts = function(_, opts)
-      vim.list_extend(opts.ensure_installed or {}, { "ktlint", "kotlin-debug-adapter" })
+      vim.list_extend(opts.ensure_installed or {}, { "ktlint" })
     end,
   },
   -- Add syntax highlighting
@@ -35,7 +35,7 @@ return {
       },
     },
   },
-  -- Add linting as optional
+  -- Add linting
   {
     "mfussenegger/nvim-lint",
     optional = true,
@@ -44,7 +44,7 @@ return {
       linters_by_ft = { kotlin = { "ktlint" } },
     },
   },
-  -- Add formatting as optional
+  -- Add formatting
   {
     "stevearc/conform.nvim",
     optional = true,
@@ -52,7 +52,7 @@ return {
       formatters_by_ft = { kotlin = { "ktlint" } },
     },
   },
-  -- Add formatting and linting as optional
+  -- Add formatting and linting
   {
     "nvimtools/none-ls.nvim",
     optional = true,
@@ -72,7 +72,7 @@ return {
     opts = function()
       local dap = require("dap")
       if not dap.adapters.kotlin then
-        require("dap").adapters.kotlin = {
+        dap.adapters.kotlin = {
           type = "executable",
           command = "kotlin-debug-adapter",
           options = { auto_continue_if_many_stopped = false },