[lldb-dap] Fix machine-overridable scope (#137723)
My previous commit was a bit sloppy, I didn't spot that
`lldb-dap.executable-path` already had a scope and I didn't consider
that `lldb-dap.log-path` should have the same scope.
This PR addresses both:
- Fix duplicate scope for `lldb-dap.executable-path`.
- Change scope of `lldb-dap.log-path` to `machine-overridable` too.
