test: remove disabled debugger test

The current debugger is slated for removal soon. The debugger test that has been disabled for over four years is unlikely to be repaired at this point. Remove the test and its associated fixture.
nodejs · Trott · Apr 4, 2017 · Apr 4, 2017 · 98e8fc01ee3adcc27a86df6df1d36bcd903b2bc1
commit 98e8fc01ee3adcc27a86df6df1d36bcd903b2bc1
diff --git a/test/disabled/test-debug-brk-file.js b/test/disabled/test-debug-brk-file.js
diff --git a/test/fixtures/debug-target.js b/test/fixtures/debug-target.js