fix(dap): don't mess up DAP adapters provided by nvim-dap-python (#4141)

## Description

* mason-nvim-dap.nvim ships a `Python: Launch file` adapter which does
the same thing as `Launch file` of nvim-dap-python, providing both
doesn't make sense and confuses the users.
* mason-nvim-dap.nvim unexpectedly overrides nvim-dap-python's adapters
and breaks its venv detection. As a result, user programs are always
executed in mason debugpy venv rather than the activated one.


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## Related Issue(s)

Fixes #3064

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## Screenshots

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## Checklist

- [X] I've read the
[CONTRIBUTING](https://github.com/LazyVim/LazyVim/blob/main/CONTRIBUTING.md)
guidelines.

lua/lazyvim/plugins/extras/lang/python.lua

@@ -138,4 +138,15 @@ return {
       table.insert(opts.auto_brackets, "python")
     end,
   },
+
+  -- Don't mess up DAP adapters provided by nvim-dap-python
+  {
+    "jay-babu/mason-nvim-dap.nvim",
+    optional = true,
+    opts = {
+      handlers = {
+        python = function() end,
+      },
+    },
+  },
 }