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.

PR-URL: #12199
Reviewed-By: Ben Noordhuis <[email protected]>
Reviewed-By: Sakthipriyan Vairamani <[email protected]>
Reviewed-By: Gibson Fahnestock <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Yuta Hiroto <[email protected]>
Reviewed-By: Richard Lau <[email protected]>