[lldb-dap] Remove the lldb-vscode symlink (NFC) (llvm#139621)

Remove the `lldb-vscode` -> `lldb-dap` symlink in the `tools` directory.
I initially created the symlink when we renamed the tool to make
migration easier. I think enough time has passed that we don't need it
anymore.

My personal motivation is that the symlink causes every file in the
`lldb-dap` directory to show up twice (once under `lldb-dap` and once
under `lldb-vscode`) in Quick Open in VS Code.

Author: JDevlieghere