Remove redundant raw detach test

The test's subject is the `disconnect` request with `restart: false,
terminateDebuggee: <true|false>` arguments, which has been covered by the
tests in `disconnect_dap_test.rb`. So this test case has become obsolete.

Co-authored-by: Andy Waite <13400+andyw8@users.noreply.github.com>

Author: 2 people