DDC debugger_test.dart golden test is broken

[vsmenon]

The test tests/dartdevc[_2]/debugger/debugger_test.dart tests custom formatting logic used in chrome and has been broken for a long while. It includes a golden file comparison - although there are two copies of the test, both point at the same golden: tests/dartdevc_2/debugger/debugger_test_golden.txt.

As best as I can tell, this golden isn't properly read (falls back to null) when run on the bots or locally. It also appears that the actual string varies on different platforms.

For now, I'll resurrect the rest of the test (which would have caught #43987) and skip the golden check.

Note, custom formatters are on the way out, so we may preferred ripping this out instead of fully fixing.

@sigmundch @nshahan @jacob314